`sqlite3` — DB-API 2.0 interface for SQLite databases¶

Вихідний код: Lib/sqlite3/

SQLite — це бібліотека C, яка надає легку дискову базу даних, яка не потребує окремого серверного процесу та дозволяє отримувати доступ до бази даних за допомогою нестандартного варіанту мови запитів SQL. Деякі програми можуть використовувати SQLite для внутрішнього зберігання даних. Також можна створити прототип програми за допомогою SQLite, а потім перенести код у більшу базу даних, таку як PostgreSQL або Oracle.

The sqlite3 module was written by Gerhard Häring. It provides an SQL interface compliant with the DB-API 2.0 specification described by PEP 249, and requires SQLite 3.7.15 or newer.

Цей документ включає в себе 4 головні розділи:

sqlite3-tutorial`вчить як використовувати :mod:!sqlite3` модуль.
Посилання описує класи і функції, які визначає цей модуль
How-to guides деталі як вирішувати певні задачі.
Пояснення надає поглиблений контекст контролю транзакцій.

Дивись також

https://www.sqlite.org: Веб-сторінка SQLite; документація описує синтаксис і доступні типи даних для підтримуваного діалекту SQL.
https://www.w3schools.com/sql/: Підручник, довідник і приклади для вивчення синтаксису SQL.
PEP 249 - Специфікація API бази даних 2.0: PEP, написаний Марком-Андре Лембургом.

Підручник¶

На цьому курсі Ви створите базу данних фільмів Монті Пайтон використовуючи базовий функціонал sqlite3. Це передбачає фундаментальне розуміння концепту баз данних, включаючи cursors і transactions.

First, we need to create a new database and open a database connection to allow sqlite3 to work with it. Call sqlite3.connect() to create a connection to the database tutorial.db in the current working directory, implicitly creating it if it does not exist:

import sqlite3
con = sqlite3.connect("tutorial.db")

Поверненний Connection об’єкт con відображає з’єднання з базою данних на диску.

Щоб виконувати SQL викази і отримувати результати із запитів SQL, нам знадобиться використовувати курсор бази даних. Викличте con.cursor() , щоб створити Cursor:

cur = con.cursor()

Now that we’ve got a database connection and a cursor, we can create a database table movie with columns for title, release year, and review score. For simplicity, we can just use column names in the table declaration – thanks to the flexible typing feature of SQLite, specifying the data types is optional. Execute the CREATE TABLE statement by calling cur.execute(...):

cur.execute("CREATE TABLE movie(title, year, score)")

We can verify that the new table has been created by querying the sqlite_master table built-in to SQLite, which should now contain an entry for the movie table definition (see The Schema Table for details). Execute that query by calling cur.execute(...), assign the result to res, and call res.fetchone() to fetch the resulting row:

>>> res = cur.execute("SELECT name FROM sqlite_master")
>>> res.fetchone()
('movie',)

We can see that the table has been created, as the query returns a tuple containing the table’s name. If we query sqlite_master for a non-existent table spam, res.fetchone() will return None:

>>> res = cur.execute("SELECT name FROM sqlite_master WHERE name='spam'")
>>> res.fetchone() is None
True

Now, add two rows of data supplied as SQL literals by executing an INSERT statement, once again by calling cur.execute(...):

cur.execute("""
    INSERT INTO movie VALUES
        ('Monty Python and the Holy Grail', 1975, 8.2),
        ('And Now for Something Completely Different', 1971, 7.5)
""")

The INSERT statement implicitly opens a transaction, which needs to be committed before changes are saved in the database (see Transaction control for details). Call con.commit() on the connection object to commit the transaction:

con.commit()

We can verify that the data was inserted correctly by executing a SELECT query. Use the now-familiar cur.execute(...) to assign the result to res, and call res.fetchall() to return all resulting rows:

>>> res = cur.execute("SELECT score FROM movie")
>>> res.fetchall()
[(8.2,), (7.5,)]

The result is a list of two tuples, one per row, each containing that row’s score value.

Now, insert three more rows by calling cur.executemany(...):

data = [
    ("Monty Python Live at the Hollywood Bowl", 1982, 7.9),
    ("Monty Python's The Meaning of Life", 1983, 7.5),
    ("Monty Python's Life of Brian", 1979, 8.0),
]
cur.executemany("INSERT INTO movie VALUES(?, ?, ?)", data)
con.commit()  # Remember to commit the transaction after executing INSERT.

Notice that ? placeholders are used to bind data to the query. Always use placeholders instead of string formatting to bind Python values to SQL statements, to avoid SQL injection attacks (see How to use placeholders to bind values in SQL queries for more details).

We can verify that the new rows were inserted by executing a SELECT query, this time iterating over the results of the query:

>>> for row in cur.execute("SELECT year, title FROM movie ORDER BY year"):
...     print(row)
(1971, 'And Now for Something Completely Different')
(1975, 'Monty Python and the Holy Grail')
(1979, "Monty Python's Life of Brian")
(1982, 'Monty Python Live at the Hollywood Bowl')
(1983, "Monty Python's The Meaning of Life")

Each row is a two-item tuple of (year, title), matching the columns selected in the query.

Finally, verify that the database has been written to disk by calling con.close() to close the existing connection, opening a new one, creating a new cursor, then querying the database:

>>> con.close()
>>> new_con = sqlite3.connect("tutorial.db")
>>> new_cur = new_con.cursor()
>>> res = new_cur.execute("SELECT title, year FROM movie ORDER BY score DESC")
>>> title, year = res.fetchone()
>>> print(f'The highest scoring Monty Python movie is {title!r}, released in {year}')
The highest scoring Monty Python movie is 'Monty Python and the Holy Grail', released in 1975

You’ve now created an SQLite database using the sqlite3 module, inserted data and retrieved values from it in multiple ways.

Дивись також

How-to guides for further reading:
Пояснення for in-depth background on transaction control.

Посилання¶

Module functions¶

sqlite3.connect(database, timeout=5.0, detect_types=0, isolation_level='DEFERRED', check_same_thread=True, factory=sqlite3.Connection, cached_statements=128, uri=False)¶

Open a connection to an SQLite database.

Параметри:

database (path-like object) – The path to the database file to be opened. You can pass ":memory:" to create an SQLite database existing only in memory, and open a connection to it.
timeout (float) – How many seconds the connection should wait before raising an OperationalError when a table is locked. If another connection opens a transaction to modify a table, that table will be locked until the transaction is committed. Default five seconds.
detect_types (int) – Control whether and how data types not natively supported by SQLite are looked up to be converted to Python types, using the converters registered with register_converter(). Set it to any combination (using |, bitwise or) of PARSE_DECLTYPES and PARSE_COLNAMES to enable this. Column names takes precedence over declared types if both flags are set. Types cannot be detected for generated fields (for example max(data)), even when the detect_types parameter is set; str will be returned instead. By default (0), type detection is disabled.
isolation_level (str | None) – The isolation_level of the connection, controlling whether and how transactions are implicitly opened. Can be "DEFERRED" (default), "EXCLUSIVE" or "IMMEDIATE"; or None to disable opening transactions implicitly. See Transaction control for more.
check_same_thread (bool) – If True (default), ProgrammingError will be raised if the database connection is used by a thread other than the one that created it. If False, the connection may be accessed in multiple threads; write operations may need to be serialized by the user to avoid data corruption. See threadsafety for more information.
factory (Connection) – A custom subclass of Connection to create the connection with, if not the default Connection class.
cached_statements (int) – The number of statements that sqlite3 should internally cache for this connection, to avoid parsing overhead. By default, 128 statements.
uri (bool) – If set to True, database is interpreted as a URI with a file path and an optional query string. The scheme part must be "file:", and the path can be relative or absolute. The query string allows passing parameters to SQLite, enabling various How to work with SQLite URIs.

Тип повернення:

Connection

Викликає подію аудиту sqlite3.connect з аргументом база даних.

Викликає подію аудиту sqlite3.connect/handle з аргументом connection_handle.

Змінено в версії 3.4: Додано параметр uri.

Змінено в версії 3.7: database тепер також може бути path-like object, а не лише рядком.

Змінено в версії 3.10: Додано подію аудиту sqlite3.connect/handle.

sqlite3.complete_statement(statement)¶

Return True if the string statement appears to contain one or more complete SQL statements. No syntactic verification or parsing of any kind is performed, other than checking that there are no unclosed string literals and the statement is terminated by a semicolon.

Наприклад:

>>> sqlite3.complete_statement("SELECT foo FROM bar;")
True
>>> sqlite3.complete_statement("SELECT foo")
False

This function may be useful during command-line input to determine if the entered text seems to form a complete SQL statement, or if additional input is needed before calling execute().

sqlite3.enable_callback_tracebacks(flag, /)¶

Enable or disable callback tracebacks. By default you will not get any tracebacks in user-defined functions, aggregates, converters, authorizer callbacks etc. If you want to debug them, you can call this function with flag set to True. Afterwards, you will get tracebacks from callbacks on sys.stderr. Use False to disable the feature again.

Register an unraisable hook handler for an improved debug experience:

>>> sqlite3.enable_callback_tracebacks(True)
>>> con = sqlite3.connect(":memory:")
>>> def evil_trace(stmt):
...     5/0
>>> con.set_trace_callback(evil_trace)
>>> def debug(unraisable):
...     print(f"{unraisable.exc_value!r} in callback {unraisable.object.__name__}")
...     print(f"Error message: {unraisable.err_msg}")
>>> import sys
>>> sys.unraisablehook = debug
>>> cur = con.execute("SELECT 1")
ZeroDivisionError('division by zero') in callback evil_trace
Error message: None

sqlite3.register_adapter(type, adapter, /)¶: Register an adapter callable to adapt the Python type type into an SQLite type. The adapter is called with a Python object of type type as its sole argument, and must return a value of a type that SQLite natively understands.

sqlite3.register_converter(typename, converter, /)¶

Register the converter callable to convert SQLite objects of type typename into a Python object of a specific type. The converter is invoked for all SQLite values of type typename; it is passed a bytes object and should return an object of the desired Python type. Consult the parameter detect_types of connect() for information regarding how type detection works.

Note: typename and the name of the type in your query are matched case-insensitively.

Module constants¶

sqlite3.PARSE_COLNAMES¶

Pass this flag value to the detect_types parameter of connect() to look up a converter function by using the type name, parsed from the query column name, as the converter dictionary key. The type name must be wrapped in square brackets ([]).

SELECT p as "p [point]" FROM test;  ! will look up converter "point"

This flag may be combined with PARSE_DECLTYPES using the | (bitwise or) operator.

sqlite3.PARSE_DECLTYPES¶

Pass this flag value to the detect_types parameter of connect() to look up a converter function using the declared types for each column. The types are declared when the database table is created. sqlite3 will look up a converter function using the first word of the declared type as the converter dictionary key. For example:

CREATE TABLE test(
   i integer primary key,  ! will look up a converter named "integer"
   p point,                ! will look up a converter named "point"
   n number(10)            ! will look up a converter named "number"
 )

This flag may be combined with PARSE_COLNAMES using the | (bitwise or) operator.

sqlite3.SQLITE_OK¶

sqlite3.SQLITE_DENY¶

sqlite3.SQLITE_IGNORE¶

Flags that should be returned by the authorizer_callback callable passed to Connection.set_authorizer(), to indicate whether:

Access is allowed (SQLITE_OK),
The SQL statement should be aborted with an error (SQLITE_DENY)
The column should be treated as a NULL value (SQLITE_IGNORE)

sqlite3.apilevel¶: Рядкова константа, що вказує підтримуваний рівень DB-API. Потрібний для DB-API. Жорстко закодований на "2.0".

sqlite3.paramstyle¶: String constant stating the type of parameter marker formatting expected by the sqlite3 module. Required by the DB-API. Hard-coded to "qmark".

Примітка

The named DB-API parameter style is also supported.

sqlite3.sqlite_version¶: Version number of the runtime SQLite library as a string.

sqlite3.sqlite_version_info¶: Version number of the runtime SQLite library as a tuple of integers.

sqlite3.threadsafety¶

Integer constant required by the DB-API 2.0, stating the level of thread safety the sqlite3 module supports. This attribute is set based on the default threading mode the underlying SQLite library is compiled with. The SQLite threading modes are:

Single-thread: In this mode, all mutexes are disabled and SQLite is unsafe to use in more than a single thread at once.
Multi-thread: In this mode, SQLite can be safely used by multiple threads provided that no single database connection is used simultaneously in two or more threads.
Serialized: In serialized mode, SQLite can be safely used by multiple threads with no restriction.

The mappings from SQLite threading modes to DB-API 2.0 threadsafety levels are as follows:

SQLite threading mode	threadsafety	SQLITE_THREADSAFE	DB-API 2.0 meaning
single-thread	0	0	Threads may not share the module
multi-thread	1	2	Threads may share the module, but not connections
serialized	3	1	Threads may share the module, connections and cursors

Змінено в версії 3.11: Set threadsafety dynamically instead of hard-coding it to 1.

sqlite3.version¶: Version number of this module as a string. This is not the version of the SQLite library.

sqlite3.version_info¶: Version number of this module as a tuple of integers. This is not the version of the SQLite library.

Connection objects¶

class sqlite3.Connection¶

Each open SQLite database is represented by a Connection object, which is created using sqlite3.connect(). Their main purpose is creating Cursor objects, and Transaction control.

Дивись також

How to use connection shortcut methods
How to use the connection context manager

Підключення до бази даних SQLite має такі атрибути та методи:

cursor(factory=Cursor)¶: Create and return a Cursor object. The cursor method accepts a single optional parameter factory. If supplied, this must be a callable returning an instance of Cursor or its subclasses.

blobopen(table, column, row, /, *, readonly=False, name='main')¶

Open a Blob handle to an existing BLOB.

Параметри:

table (str) – The name of the table where the blob is located.
column (str) – The name of the column where the blob is located.
row (str) – The name of the row where the blob is located.
readonly (bool) – Set to True if the blob should be opened without write permissions. Defaults to False.
name (str) – The name of the database where the blob is located. Defaults to "main".

Викликає:

OperationalError – When trying to open a blob in a WITHOUT ROWID table.

Тип повернення:

Blob

Примітка

The blob size cannot be changed using the Blob class. Use the SQL function zeroblob to create a blob with a fixed size.

Нове в версії 3.11.

commit()¶: Commit any pending transaction to the database. If there is no open transaction, this method is a no-op.

rollback()¶: Roll back to the start of any pending transaction. If there is no open transaction, this method is a no-op.

close()¶: Close the database connection. Any pending transaction is not committed implicitly; make sure to commit() before closing to avoid losing pending changes.

execute(sql, parameters=(), /)¶: Створіть новий об’єкт Cursor і викличте execute() для нього з заданими sql і параметрами. Повернути новий об’єкт курсору.

executemany(sql, parameters, /)¶: Створіть новий об’єкт Cursor і викличте executemany() для нього з заданими sql і параметрами. Повернути новий об’єкт курсору.

executescript(sql_script, /)¶: Створіть новий об’єкт Cursor і викличте executescript() для нього за допомогою заданого sql_script. Повернути новий об’єкт курсору.

create_function(name, narg, func, *, deterministic=False)¶

Create or remove a user-defined SQL function.

Параметри:

name (str) – The name of the SQL function.
narg (int) – The number of arguments the SQL function can accept. If -1, it may take any number of arguments.
func (callback | None) – A callable that is called when the SQL function is invoked. The callable must return a type natively supported by SQLite. Set to None to remove an existing SQL function.
deterministic (bool) – If True, the created SQL function is marked as deterministic, which allows SQLite to perform additional optimizations.

Викликає:

NotSupportedError – If deterministic is used with SQLite versions older than 3.8.3.

Змінено в версії 3.8: Added the deterministic parameter.

приклад:

>>> import hashlib
>>> def md5sum(t):
...     return hashlib.md5(t).hexdigest()
>>> con = sqlite3.connect(":memory:")
>>> con.create_function("md5", 1, md5sum)
>>> for row in con.execute("SELECT md5(?)", (b"foo",)):
...     print(row)
('acbd18db4cc2f85cedef654fccc4a4d8',)

create_aggregate(name, n_arg, aggregate_class)¶

Create or remove a user-defined SQL aggregate function.

Параметри:

name (str) – The name of the SQL aggregate function.
n_arg (int) – The number of arguments the SQL aggregate function can accept. If -1, it may take any number of arguments.
aggregate_class (class | None) –
A class must implement the following methods:
- step(): Add a row to the aggregate.
- finalize(): Return the final result of the aggregate as a type natively supported by SQLite.
The number of arguments that the step() method must accept is controlled by n_arg.

Set to None to remove an existing SQL aggregate function.

приклад:

class MySum:
    def __init__(self):
        self.count = 0

    def step(self, value):
        self.count += value

    def finalize(self):
        return self.count

con = sqlite3.connect(":memory:")
con.create_aggregate("mysum", 1, MySum)
cur = con.execute("CREATE TABLE test(i)")
cur.execute("INSERT INTO test(i) VALUES(1)")
cur.execute("INSERT INTO test(i) VALUES(2)")
cur.execute("SELECT mysum(i) FROM test")
print(cur.fetchone()[0])

con.close()

create_window_function(name, num_params, aggregate_class, /)¶

Create or remove a user-defined aggregate window function.

Параметри:

name (str) – The name of the SQL aggregate window function to create or remove.
num_params (int) – The number of arguments the SQL aggregate window function can accept. If -1, it may take any number of arguments.
aggregate_class (class | None) –
A class that must implement the following methods:
- step(): Add a row to the current window.
- value(): Return the current value of the aggregate.
- inverse(): Remove a row from the current window.
- finalize(): Return the final result of the aggregate as a type natively supported by SQLite.
The number of arguments that the step() and value() methods must accept is controlled by num_params.

Set to None to remove an existing SQL aggregate window function.

Викликає:

NotSupportedError – If used with a version of SQLite older than 3.25.0, which does not support aggregate window functions.

Нове в версії 3.11.

приклад:

# Example taken from https://www.sqlite.org/windowfunctions.html#udfwinfunc
class WindowSumInt:
    def __init__(self):
        self.count = 0

    def step(self, value):
        """Add a row to the current window."""
        self.count += value

    def value(self):
        """Return the current value of the aggregate."""
        return self.count

    def inverse(self, value):
        """Remove a row from the current window."""
        self.count -= value

    def finalize(self):
        """Return the final value of the aggregate.

        Any clean-up actions should be placed here.
        """
        return self.count


con = sqlite3.connect(":memory:")
cur = con.execute("CREATE TABLE test(x, y)")
values = [
    ("a", 4),
    ("b", 5),
    ("c", 3),
    ("d", 8),
    ("e", 1),
]
cur.executemany("INSERT INTO test VALUES(?, ?)", values)
con.create_window_function("sumint", 1, WindowSumInt)
cur.execute("""
    SELECT x, sumint(y) OVER (
        ORDER BY x ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING
    ) AS sum_y
    FROM test ORDER BY x
""")
print(cur.fetchall())

create_collation(name, callable, /)¶

Створіть зіставлення під назвою name за допомогою функції зіставлення callable. callable передається два аргументи string, і він має повернути ціле число:

1, якщо перший впорядкований вище за другий
-1, якщо перший впорядкований нижче другого
0, якщо вони в порядку рівності

У наступному прикладі показано порівняння зворотного сортування:

def collate_reverse(string1, string2):
    if string1 == string2:
        return 0
    elif string1 < string2:
        return 1
    else:
        return -1

con = sqlite3.connect(":memory:")
con.create_collation("reverse", collate_reverse)

cur = con.execute("CREATE TABLE test(x)")
cur.executemany("INSERT INTO test(x) VALUES(?)", [("a",), ("b",)])
cur.execute("SELECT x FROM test ORDER BY x COLLATE reverse")
for row in cur:
    print(row)
con.close()

Remove a collation function by setting callable to None.

Змінено в версії 3.11: The collation name can contain any Unicode character. Earlier, only ASCII characters were allowed.

interrupt()¶: Call this method from a different thread to abort any queries that might be executing on the connection. Aborted queries will raise an OperationalError.

set_authorizer(authorizer_callback)¶

Register callable authorizer_callback to be invoked for each attempt to access a column of a table in the database. The callback should return one of SQLITE_OK, SQLITE_DENY, or SQLITE_IGNORE to signal how access to the column should be handled by the underlying SQLite library.

The first argument to the callback signifies what kind of operation is to be authorized. The second and third argument will be arguments or None depending on the first argument. The 4th argument is the name of the database («main», «temp», etc.) if applicable. The 5th argument is the name of the inner-most trigger or view that is responsible for the access attempt or None if this access attempt is directly from input SQL code.

Please consult the SQLite documentation about the possible values for the first argument and the meaning of the second and third argument depending on the first one. All necessary constants are available in the sqlite3 module.

Passing None as authorizer_callback will disable the authorizer.

Змінено в версії 3.11: Added support for disabling the authorizer using None.

set_progress_handler(progress_handler, n)¶

Register callable progress_handler to be invoked for every n instructions of the SQLite virtual machine. This is useful if you want to get called from SQLite during long-running operations, for example to update a GUI.

If you want to clear any previously installed progress handler, call the method with None for progress_handler.

Returning a non-zero value from the handler function will terminate the currently executing query and cause it to raise an OperationalError exception.

set_trace_callback(trace_callback)¶

Register callable trace_callback to be invoked for each SQL statement that is actually executed by the SQLite backend.

The only argument passed to the callback is the statement (as str) that is being executed. The return value of the callback is ignored. Note that the backend does not only run statements passed to the Cursor.execute() methods. Other sources include the transaction management of the sqlite3 module and the execution of triggers defined in the current database.

Passing None as trace_callback will disable the trace callback.

Примітка

Винятки, викликані зворотним викликом трасування, не поширюються. Як допомога при розробці та налагодженні використовуйте enable_callback_tracebacks(), щоб увімкнути друк трасування з винятків, викликаних у зворотному виклику трасування.

Нове в версії 3.3.

enable_load_extension(enabled, /)¶

Enable the SQLite engine to load SQLite extensions from shared libraries if enabled is True; else, disallow loading SQLite extensions. SQLite extensions can define new functions, aggregates or whole new virtual table implementations. One well-known extension is the fulltext-search extension distributed with SQLite.

Примітка

The sqlite3 module is not built with loadable extension support by default, because some platforms (notably macOS) have SQLite libraries which are compiled without this feature. To get loadable extension support, you must pass the --enable-loadable-sqlite-extensions option to configure.

Викликає подію аудиту sqlite3.enable_load_extension з аргументами connection, enabled.

Нове в версії 3.2.

Змінено в версії 3.10: Додано подію аудиту sqlite3.enable_load_extension.

con.enable_load_extension(True)

# Load the fulltext search extension
con.execute("select load_extension('./fts3.so')")

# alternatively you can load the extension using an API call:
# con.load_extension("./fts3.so")

# disable extension loading again
con.enable_load_extension(False)

# example from SQLite wiki
con.execute("CREATE VIRTUAL TABLE recipe USING fts3(name, ingredients)")
con.executescript("""
    INSERT INTO recipe (name, ingredients) VALUES('broccoli stew', 'broccoli peppers cheese tomatoes');
    INSERT INTO recipe (name, ingredients) VALUES('pumpkin stew', 'pumpkin onions garlic celery');
    INSERT INTO recipe (name, ingredients) VALUES('broccoli pie', 'broccoli cheese onions flour');
    INSERT INTO recipe (name, ingredients) VALUES('pumpkin pie', 'pumpkin sugar flour butter');
    """)
for row in con.execute("SELECT rowid, name, ingredients FROM recipe WHERE name MATCH 'pie'"):
    print(row)

con.close()

load_extension(path, /)¶

Load an SQLite extension from a shared library located at path. Enable extension loading with enable_load_extension() before calling this method.

Викликає подію аудиту sqlite3.load_extension з аргументами connection, path.

Нове в версії 3.2.

Змінено в версії 3.10: Додано подію аудиту sqlite3.load_extension.

iterdump()¶

Return an iterator to dump the database as SQL source code. Useful when saving an in-memory database for later restoration. Similar to the .dump command in the sqlite3 shell.

приклад:

# Convert file example.db to SQL dump file dump.sql
con = sqlite3.connect('example.db')
with open('dump.sql', 'w') as f:
    for line in con.iterdump():
        f.write('%s\n' % line)
con.close()

Дивись також

How to handle non-UTF-8 text encodings

backup(target, *, pages=-1, progress=None, name='main', sleep=0.250)¶

Create a backup of an SQLite database.

Works even if the database is being accessed by other clients or concurrently by the same connection.

Параметри:

target (Connection) – The database connection to save the backup to.
pages (int) – The number of pages to copy at a time. If equal to or less than 0, the entire database is copied in a single step. Defaults to -1.
progress (callback | None) – If set to a callable, it is invoked with three integer arguments for every backup iteration: the status of the last iteration, the remaining number of pages still to be copied, and the total number of pages. Defaults to None.
name (str) – The name of the database to back up. Either "main" (the default) for the main database, "temp" for the temporary database, or the name of a custom database as attached using the ATTACH DATABASE SQL statement.
sleep (float) – The number of seconds to sleep between successive attempts to back up remaining pages.

Example 1, copy an existing database into another:

def progress(status, remaining, total):
    print(f'Copied {total-remaining} of {total} pages...')

src = sqlite3.connect('example.db')
dst = sqlite3.connect('backup.db')
with dst:
    src.backup(dst, pages=1, progress=progress)
dst.close()
src.close()

Example 2, copy an existing database into a transient copy:

src = sqlite3.connect('example.db')
dst = sqlite3.connect(':memory:')
src.backup(dst)

Нове в версії 3.7.

Дивись також

How to handle non-UTF-8 text encodings

getlimit(category, /)¶

Get a connection runtime limit.

Параметри:: category (int) – The SQLite limit category to be queried.
Тип повернення:: int
Викликає:: ProgrammingError – If category is not recognised by the underlying SQLite library.

Example, query the maximum length of an SQL statement for Connection con (the default is 1000000000):

>>> con.getlimit(sqlite3.SQLITE_LIMIT_SQL_LENGTH)
1000000000

Нове в версії 3.11.

setlimit(category, limit, /)¶

Set a connection runtime limit. Attempts to increase a limit above its hard upper bound are silently truncated to the hard upper bound. Regardless of whether or not the limit was changed, the prior value of the limit is returned.

Параметри:

category (int) – The SQLite limit category to be set.
limit (int) – The value of the new limit. If negative, the current limit is unchanged.

Тип повернення:

int

Викликає:

ProgrammingError – If category is not recognised by the underlying SQLite library.

Example, limit the number of attached databases to 1 for Connection con (the default limit is 10):

>>> con.setlimit(sqlite3.SQLITE_LIMIT_ATTACHED, 1)
10
>>> con.getlimit(sqlite3.SQLITE_LIMIT_ATTACHED)
1

Нове в версії 3.11.

serialize(*, name='main')¶

Serialize a database into a bytes object. For an ordinary on-disk database file, the serialization is just a copy of the disk file. For an in-memory database or a «temp» database, the serialization is the same sequence of bytes which would be written to disk if that database were backed up to disk.

Параметри:: name (str) – The database name to be serialized. Defaults to "main".
Тип повернення:: bytes

Примітка

This method is only available if the underlying SQLite library has the serialize API.

Нове в версії 3.11.

deserialize(data, /, *, name='main')¶

Deserialize a serialized database into a Connection. This method causes the database connection to disconnect from database name, and reopen name as an in-memory database based on the serialization contained in data.

Параметри:

data (bytes) – A serialized database.
name (str) – The database name to deserialize into. Defaults to "main".

Викликає:

OperationalError – If the database connection is currently involved in a read transaction or a backup operation.
DatabaseError – If data does not contain a valid SQLite database.
OverflowError – If len(data) is larger than 2**63 - 1.

Примітка

This method is only available if the underlying SQLite library has the deserialize API.

Нове в версії 3.11.

in_transaction¶

This read-only attribute corresponds to the low-level SQLite autocommit mode.

True if a transaction is active (there are uncommitted changes), False otherwise.

Нове в версії 3.2.

isolation_level¶

This attribute controls the transaction handling performed by sqlite3. If set to None, transactions are never implicitly opened. If set to one of "DEFERRED", "IMMEDIATE", or "EXCLUSIVE", corresponding to the underlying SQLite transaction behaviour, implicit transaction management is performed.

If not overridden by the isolation_level parameter of connect(), the default is "", which is an alias for "DEFERRED".

row_factory¶

The initial row_factory for Cursor objects created from this connection. Assigning to this attribute does not affect the row_factory of existing cursors belonging to this connection, only new ones. Is None by default, meaning each row is returned as a tuple.

See How to create and use row factories for more details.

text_factory¶

A callable that accepts a bytes parameter and returns a text representation of it. The callable is invoked for SQLite values with the TEXT data type. By default, this attribute is set to str.

See How to handle non-UTF-8 text encodings for more details.

total_changes¶: Return the total number of database rows that have been modified, inserted, or deleted since the database connection was opened.

Cursor objects¶

A Cursor object represents a database cursor which is used to execute SQL statements, and manage the context of a fetch operation. Cursors are created using Connection.cursor(), or by using any of the connection shortcut methods.

Cursor objects are iterators, meaning that if you execute() a SELECT query, you can simply iterate over the cursor to fetch the resulting rows:
for row in cur.execute("SELECT t FROM data"):
    print(row)

class sqlite3.Cursor¶

Екземпляр Cursor має такі атрибути та методи.

execute(sql, parameters=(), /)¶

Execute a single SQL statement, optionally binding Python values using placeholders.

Параметри:

sql (str) – A single SQL statement.
parameters (dict | sequence) – Python values to bind to placeholders in sql. A dict if named placeholders are used. A sequence if unnamed placeholders are used. See How to use placeholders to bind values in SQL queries.

Викликає:

ProgrammingError – If sql contains more than one SQL statement.

If isolation_level is not None, sql is an INSERT, UPDATE, DELETE, or REPLACE statement, and there is no open transaction, a transaction is implicitly opened before executing sql.

Use executescript() to execute multiple SQL statements.

executemany(sql, parameters, /)¶

For every item in parameters, repeatedly execute the parameterized DML SQL statement sql.

Uses the same implicit transaction handling as execute().

Параметри:

sql (str) – A single SQL DML statement.
parameters (iterable) – An iterable of parameters to bind with the placeholders in sql. See How to use placeholders to bind values in SQL queries.

Викликає:

ProgrammingError – If sql contains more than one SQL statement, or is not a DML statement.

приклад:

rows = [
    ("row1",),
    ("row2",),
]
# cur is an sqlite3.Cursor object
cur.executemany("INSERT INTO data VALUES(?)", rows)

Примітка

Any resulting rows are discarded, including DML statements with RETURNING clauses.

executescript(sql_script, /)¶

Execute the SQL statements in sql_script. If there is a pending transaction, an implicit COMMIT statement is executed first. No other implicit transaction control is performed; any transaction control must be added to sql_script.

sql_script must be a string.

приклад:

# cur is an sqlite3.Cursor object
cur.executescript("""
    BEGIN;
    CREATE TABLE person(firstname, lastname, age);
    CREATE TABLE book(title, author, published);
    CREATE TABLE publisher(name, address);
    COMMIT;
""")

fetchone()¶: If row_factory is None, return the next row query result set as a tuple. Else, pass it to the row factory and return its result. Return None if no more data is available.

fetchmany(size=cursor.arraysize)¶

Return the next set of rows of a query result as a list. Return an empty list if no more rows are available.

The number of rows to fetch per call is specified by the size parameter. If size is not given, arraysize determines the number of rows to be fetched. If fewer than size rows are available, as many rows as are available are returned.

Зауважте, що з параметром size пов’язані міркування щодо продуктивності. Для оптимальної продуктивності зазвичай найкраще використовувати атрибут arraysize. Якщо використовується параметр size, то найкраще, щоб він зберігав те саме значення від одного виклику fetchmany() до наступного.

fetchall()¶: Return all (remaining) rows of a query result as a list. Return an empty list if no rows are available. Note that the arraysize attribute can affect the performance of this operation.

close()¶

Закрийте курсор зараз (а не під час кожного виклику __del__).

Курсор стане непридатним для використання з цього моменту; виняток ProgrammingError буде викликано, якщо будь-яка операція буде виконана з курсором.

setinputsizes(sizes, /)¶: Required by the DB-API. Does nothing in sqlite3.

setoutputsize(size, column=None, /)¶: Required by the DB-API. Does nothing in sqlite3.

arraysize¶: Атрибут читання/запису, який контролює кількість рядків, які повертає fetchmany(). Значення за замовчуванням дорівнює 1, що означає, що за виклик буде отримано один рядок.

connection¶

Read-only attribute that provides the SQLite database Connection belonging to the cursor. A Cursor object created by calling con.cursor() will have a connection attribute that refers to con:

>>> con = sqlite3.connect(":memory:")
>>> cur = con.cursor()
>>> cur.connection == con
True

description¶

Read-only attribute that provides the column names of the last query. To remain compatible with the Python DB API, it returns a 7-tuple for each column where the last six items of each tuple are None.

Він також встановлений для операторів SELECT без будь-яких відповідних рядків.

lastrowid¶: Read-only attribute that provides the row id of the last inserted row. It is only updated after successful INSERT or REPLACE statements using the execute() method. For other statements, after executemany() or executescript(), or if the insertion failed, the value of lastrowid is left unchanged. The initial value of lastrowid is None.

Примітка

Вставки в таблиці БЕЗ ROWID не записуються.

Змінено в версії 3.6: Додано підтримку оператора REPLACE.

rowcount¶: Read-only attribute that provides the number of modified rows for INSERT, UPDATE, DELETE, and REPLACE statements; is -1 for other statements, including CTE queries. It is only updated by the execute() and executemany() methods, after the statement has run to completion. This means that any resulting rows must be fetched in order for rowcount to be updated.

row_factory¶

Control how a row fetched from this Cursor is represented. If None, a row is represented as a tuple. Can be set to the included sqlite3.Row; or a callable that accepts two arguments, a Cursor object and the tuple of row values, and returns a custom object representing an SQLite row.

Defaults to what Connection.row_factory was set to when the Cursor was created. Assigning to this attribute does not affect Connection.row_factory of the parent connection.

See How to create and use row factories for more details.

Row objects¶

class sqlite3.Row¶

A Row instance serves as a highly optimized row_factory for Connection objects. It supports iteration, equality testing, len(), and mapping access by column name and index.

Two Row objects compare equal if they have identical column names and values.

See How to create and use row factories for more details.

keys()¶: Return a list of column names as strings. Immediately after a query, it is the first member of each tuple in Cursor.description.

Змінено в версії 3.5: Додана підтримка нарізки.

Blob objects¶

class sqlite3.Blob¶

Нове в версії 3.11.

A Blob instance is a file-like object that can read and write data in an SQLite BLOB. Call len(blob) to get the size (number of bytes) of the blob. Use indices and slices for direct access to the blob data.

Use the Blob as a context manager to ensure that the blob handle is closed after use.

con = sqlite3.connect(":memory:")
con.execute("CREATE TABLE test(blob_col blob)")
con.execute("INSERT INTO test(blob_col) VALUES(zeroblob(13))")

# Write to our blob, using two write operations:
with con.blobopen("test", "blob_col", 1) as blob:
    blob.write(b"hello, ")
    blob.write(b"world.")
    # Modify the first and last bytes of our blob
    blob[0] = ord("H")
    blob[-1] = ord("!")

# Read the contents of our blob
with con.blobopen("test", "blob_col", 1) as blob:
    greeting = blob.read()

print(greeting)  # outputs "b'Hello, world!'"

close()¶

Close the blob.

The blob will be unusable from this point onward. An Error (or subclass) exception will be raised if any further operation is attempted with the blob.

read(length=-1, /)¶: Read length bytes of data from the blob at the current offset position. If the end of the blob is reached, the data up to EOF will be returned. When length is not specified, or is negative, read() will read until the end of the blob.

write(data, /)¶: Write data to the blob at the current offset. This function cannot change the blob length. Writing beyond the end of the blob will raise ValueError.

tell()¶: Return the current access position of the blob.

seek(offset, origin=os.SEEK_SET, /)¶: Set the current access position of the blob to offset. The origin argument defaults to os.SEEK_SET (absolute blob positioning). Other values for origin are os.SEEK_CUR (seek relative to the current position) and os.SEEK_END (seek relative to the blob’s end).

PrepareProtocol objects¶

class sqlite3.PrepareProtocol¶: The PrepareProtocol type’s single purpose is to act as a PEP 246 style adaption protocol for objects that can adapt themselves to native SQLite types.

Винятки¶

Ієрархія винятків визначається DB-API 2.0 (PEP 249).

exception sqlite3.Warning¶: This exception is not currently raised by the sqlite3 module, but may be raised by applications using sqlite3, for example if a user-defined function truncates data while inserting. Warning is a subclass of Exception.

exception sqlite3.Error¶

Базовий клас інших винятків у цьому модулі. Використовуйте це, щоб перехопити всі помилки за допомогою одного оператора except. Error є підкласом Exception.

If the exception originated from within the SQLite library, the following two attributes are added to the exception:

sqlite_errorcode¶: The numeric error code from the SQLite API

Нове в версії 3.11.

sqlite_errorname¶: The symbolic name of the numeric error code from the SQLite API

Нове в версії 3.11.

exception sqlite3.InterfaceError¶: Exception raised for misuse of the low-level SQLite C API. In other words, if this exception is raised, it probably indicates a bug in the sqlite3 module. InterfaceError is a subclass of Error.

exception sqlite3.DatabaseError¶: Виняток створено для помилок, пов’язаних із базою даних. Це служить базовим винятком для кількох типів помилок бази даних. Він виникає лише неявно через спеціалізовані підкласи. DatabaseError є підкласом Error.

exception sqlite3.DataError¶: Виняток створено для помилок, спричинених проблемами з обробленими даними, як-от числові значення поза межами діапазону та надто довгі рядки. DataError є підкласом DatabaseError.

exception sqlite3.OperationalError¶: Виняток створено для помилок, які пов’язані з роботою бази даних і не обов’язково знаходяться під контролем програміста. Наприклад, шлях до бази даних не знайдено або транзакцію не вдалося обробити. OperationalError є підкласом DatabaseError.

exception sqlite3.IntegrityError¶: Виняток виникає, коли порушується реляційна цілісність бази даних, наприклад. не вдається перевірити зовнішній ключ. Це підклас DatabaseError.

exception sqlite3.InternalError¶: Виняток виникає, коли SQLite стикається з внутрішньою помилкою. Якщо це виникає, це може означати, що існує проблема з бібліотекою SQLite під час виконання. InternalError є підкласом DatabaseError.

exception sqlite3.ProgrammingError¶: Exception raised for sqlite3 API programming errors, for example supplying the wrong number of bindings to a query, or trying to operate on a closed Connection. ProgrammingError is a subclass of DatabaseError.

exception sqlite3.NotSupportedError¶: Exception raised in case a method or database API is not supported by the underlying SQLite library. For example, setting deterministic to True in create_function(), if the underlying SQLite library does not support deterministic functions. NotSupportedError is a subclass of DatabaseError.

Типи SQLite і Python¶

SQLite спочатку підтримує такі типи: NULL, INTEGER, REAL, TEXT, BLOB.

Таким чином, такі типи Python можна без будь-яких проблем надсилати до SQLite:

Тип Python	Тип SQLite
`Жодного`	`NULL`
`int`	`ЦІЛЕ ЧИСЛО`
`float`	`РЕАЛЬНИЙ`
`str`	`ТЕКСТ`
`bytes`	`BLOB`

Ось як типи SQLite перетворюються на типи Python за замовчуванням:

Тип SQLite	Тип Python
`NULL`	`Жодного`
`ЦІЛЕ ЧИСЛО`	`int`
`РЕАЛЬНИЙ`	`float`
`ТЕКСТ`	залежить від `text_factory`, `str` за замовчуванням
`BLOB`	`bytes`

The type system of the sqlite3 module is extensible in two ways: you can store additional Python types in an SQLite database via object adapters, and you can let the sqlite3 module convert SQLite types to Python types via converters.

Default adapters and converters¶

There are default adapters for the date and datetime types in the datetime module. They will be sent as ISO dates/ISO timestamps to SQLite.

The default converters are registered under the name «date» for datetime.date and under the name «timestamp» for datetime.datetime.

This way, you can use date/timestamps from Python without any additional fiddling in most cases. The format of the adapters is also compatible with the experimental SQLite date/time functions.

The following example demonstrates this.

import sqlite3
import datetime

con = sqlite3.connect(":memory:", detect_types=sqlite3.PARSE_DECLTYPES|sqlite3.PARSE_COLNAMES)
cur = con.cursor()
cur.execute("create table test(d date, ts timestamp)")

today = datetime.date.today()
now = datetime.datetime.now()

cur.execute("insert into test(d, ts) values (?, ?)", (today, now))
cur.execute("select d, ts from test")
row = cur.fetchone()
print(today, "=>", row[0], type(row[0]))
print(now, "=>", row[1], type(row[1]))

cur.execute('select current_date as "d [date]", current_timestamp as "ts [timestamp]"')
row = cur.fetchone()
print("current_date", row[0], type(row[0]))
print("current_timestamp", row[1], type(row[1]))

con.close()

If a timestamp stored in SQLite has a fractional part longer than 6 numbers, its value will be truncated to microsecond precision by the timestamp converter.

Примітка

Конвертер «міток часу» за замовчуванням ігнорує зміщення UTC у базі даних і завжди повертає простий об’єкт datetime.datetime. Щоб зберегти зміщення UTC у мітках часу, залиште конвертери вимкненими або зареєструйте конвертер із зсувом за допомогою register_converter().

How-to guides¶

How to use placeholders to bind values in SQL queries¶

SQL operations usually need to use values from Python variables. However, beware of using Python’s string operations to assemble queries, as they are vulnerable to SQL injection attacks. For example, an attacker can simply close the single quote and inject OR TRUE to select all rows:

>>> # Never do this -- insecure!
>>> symbol = input()
' OR TRUE; --
>>> sql = "SELECT * FROM stocks WHERE symbol = '%s'" % symbol
>>> print(sql)
SELECT * FROM stocks WHERE symbol = '' OR TRUE; --'
>>> cur.execute(sql)

Instead, use the DB-API’s parameter substitution. To insert a variable into a query string, use a placeholder in the string, and substitute the actual values into the query by providing them as a tuple of values to the second argument of the cursor’s execute() method.

An SQL statement may use one of two kinds of placeholders: question marks (qmark style) or named placeholders (named style). For the qmark style, parameters must be a sequence whose length must match the number of placeholders, or a ProgrammingError is raised. For the named style, parameters should be an instance of a dict (or a subclass), which must contain keys for all named parameters; any extra items are ignored. Here’s an example of both styles:

con = sqlite3.connect(":memory:")
cur = con.execute("CREATE TABLE lang(name, first_appeared)")

# This is the named style used with executemany():
data = (
    {"name": "C", "year": 1972},
    {"name": "Fortran", "year": 1957},
    {"name": "Python", "year": 1991},
    {"name": "Go", "year": 2009},
)
cur.executemany("INSERT INTO lang VALUES(:name, :year)", data)

# This is the qmark style used in a SELECT query:
params = (1972,)
cur.execute("SELECT * FROM lang WHERE first_appeared = ?", params)
print(cur.fetchall())

Примітка

PEP 249 numeric placeholders are not supported. If used, they will be interpreted as named placeholders.

How to adapt custom Python types to SQLite values¶

SQLite supports only a limited set of data types natively. To store custom Python types in SQLite databases, adapt them to one of the Python types SQLite natively understands.

There are two ways to adapt Python objects to SQLite types: letting your object adapt itself, or using an adapter callable. The latter will take precedence above the former. For a library that exports a custom type, it may make sense to enable that type to adapt itself. As an application developer, it may make more sense to take direct control by registering custom adapter functions.

How to write adaptable objects¶

Suppose we have a Point class that represents a pair of coordinates, x and y, in a Cartesian coordinate system. The coordinate pair will be stored as a text string in the database, using a semicolon to separate the coordinates. This can be implemented by adding a __conform__(self, protocol) method which returns the adapted value. The object passed to protocol will be of type PrepareProtocol.

class Point:
    def __init__(self, x, y):
        self.x, self.y = x, y

    def __conform__(self, protocol):
        if protocol is sqlite3.PrepareProtocol:
            return f"{self.x};{self.y}"

con = sqlite3.connect(":memory:")
cur = con.cursor()

cur.execute("SELECT ?", (Point(4.0, -3.2),))
print(cur.fetchone()[0])

How to register adapter callables¶

The other possibility is to create a function that converts the Python object to an SQLite-compatible type. This function can then be registered using register_adapter().

class Point:
    def __init__(self, x, y):
        self.x, self.y = x, y

def adapt_point(point):
    return f"{point.x};{point.y}"

sqlite3.register_adapter(Point, adapt_point)

con = sqlite3.connect(":memory:")
cur = con.cursor()

cur.execute("SELECT ?", (Point(1.0, 2.5),))
print(cur.fetchone()[0])

How to convert SQLite values to custom Python types¶

Writing an adapter lets you convert from custom Python types to SQLite values. To be able to convert from SQLite values to custom Python types, we use converters.

Let’s go back to the Point class. We stored the x and y coordinates separated via semicolons as strings in SQLite.

First, we’ll define a converter function that accepts the string as a parameter and constructs a Point object from it.

Примітка

Converter functions are always passed a bytes object, no matter the underlying SQLite data type.

def convert_point(s):
    x, y = map(float, s.split(b";"))
    return Point(x, y)

We now need to tell sqlite3 when it should convert a given SQLite value. This is done when connecting to a database, using the detect_types parameter of connect(). There are three options:

Implicit: set detect_types to PARSE_DECLTYPES
Explicit: set detect_types to PARSE_COLNAMES
Both: set detect_types to sqlite3.PARSE_DECLTYPES | sqlite3.PARSE_COLNAMES. Column names take precedence over declared types.

The following example illustrates the implicit and explicit approaches:

class Point:
    def __init__(self, x, y):
        self.x, self.y = x, y

    def __repr__(self):
        return f"Point({self.x}, {self.y})"

def adapt_point(point):
    return f"{point.x};{point.y}"

def convert_point(s):
    x, y = list(map(float, s.split(b";")))
    return Point(x, y)

# Register the adapter and converter
sqlite3.register_adapter(Point, adapt_point)
sqlite3.register_converter("point", convert_point)

# 1) Parse using declared types
p = Point(4.0, -3.2)
con = sqlite3.connect(":memory:", detect_types=sqlite3.PARSE_DECLTYPES)
cur = con.execute("CREATE TABLE test(p point)")

cur.execute("INSERT INTO test(p) VALUES(?)", (p,))
cur.execute("SELECT p FROM test")
print("with declared types:", cur.fetchone()[0])
cur.close()
con.close()

# 2) Parse using column names
con = sqlite3.connect(":memory:", detect_types=sqlite3.PARSE_COLNAMES)
cur = con.execute("CREATE TABLE test(p)")

cur.execute("INSERT INTO test(p) VALUES(?)", (p,))
cur.execute('SELECT p AS "p [point]" FROM test')
print("with column names:", cur.fetchone()[0])

Adapter and converter recipes¶

This section shows recipes for common adapters and converters.

import datetime
import sqlite3

def adapt_date_iso(val):
    """Adapt datetime.date to ISO 8601 date."""
    return val.isoformat()

def adapt_datetime_iso(val):
    """Adapt datetime.datetime to timezone-naive ISO 8601 date."""
    return val.isoformat()

def adapt_datetime_epoch(val):
    """Adapt datetime.datetime to Unix timestamp."""
    return int(val.timestamp())

sqlite3.register_adapter(datetime.date, adapt_date_iso)
sqlite3.register_adapter(datetime.datetime, adapt_datetime_iso)
sqlite3.register_adapter(datetime.datetime, adapt_datetime_epoch)

def convert_date(val):
    """Convert ISO 8601 date to datetime.date object."""
    return datetime.date.fromisoformat(val.decode())

def convert_datetime(val):
    """Convert ISO 8601 datetime to datetime.datetime object."""
    return datetime.datetime.fromisoformat(val.decode())

def convert_timestamp(val):
    """Convert Unix epoch timestamp to datetime.datetime object."""
    return datetime.datetime.fromtimestamp(int(val))

sqlite3.register_converter("date", convert_date)
sqlite3.register_converter("datetime", convert_datetime)
sqlite3.register_converter("timestamp", convert_timestamp)

How to use connection shortcut methods¶

Using the execute(), executemany(), and executescript() methods of the Connection class, your code can be written more concisely because you don’t have to create the (often superfluous) Cursor objects explicitly. Instead, the Cursor objects are created implicitly and these shortcut methods return the cursor objects. This way, you can execute a SELECT statement and iterate over it directly using only a single call on the Connection object.

# Create and fill the table.
con = sqlite3.connect(":memory:")
con.execute("CREATE TABLE lang(name, first_appeared)")
data = [
    ("C++", 1985),
    ("Objective-C", 1984),
]
con.executemany("INSERT INTO lang(name, first_appeared) VALUES(?, ?)", data)

# Print the table contents
for row in con.execute("SELECT name, first_appeared FROM lang"):
    print(row)

print("I just deleted", con.execute("DELETE FROM lang").rowcount, "rows")

# close() is not a shortcut method and it's not called automatically;
# the connection object should be closed manually
con.close()

How to use the connection context manager¶

A Connection object can be used as a context manager that automatically commits or rolls back open transactions when leaving the body of the context manager. If the body of the with statement finishes without exceptions, the transaction is committed. If this commit fails, or if the body of the with statement raises an uncaught exception, the transaction is rolled back.

If there is no open transaction upon leaving the body of the with statement, the context manager is a no-op.

Примітка

The context manager neither implicitly opens a new transaction nor closes the connection. If you need a closing context manager, consider using contextlib.closing().

con = sqlite3.connect(":memory:")
con.execute("CREATE TABLE lang(id INTEGER PRIMARY KEY, name VARCHAR UNIQUE)")

# Successful, con.commit() is called automatically afterwards
with con:
    con.execute("INSERT INTO lang(name) VALUES(?)", ("Python",))

# con.rollback() is called after the with block finishes with an exception,
# the exception is still raised and must be caught
try:
    with con:
        con.execute("INSERT INTO lang(name) VALUES(?)", ("Python",))
except sqlite3.IntegrityError:
    print("couldn't add Python twice")

# Connection object used as context manager only commits or rollbacks transactions,
# so the connection object should be closed manually
con.close()

How to work with SQLite URIs¶

Some useful URI tricks include:

Open a database in read-only mode:

>>> con = sqlite3.connect("file:tutorial.db?mode=ro", uri=True)
>>> con.execute("CREATE TABLE readonly(data)")
Traceback (most recent call last):
OperationalError: attempt to write a readonly database

Do not implicitly create a new database file if it does not already exist; will raise OperationalError if unable to create a new file:

>>> con = sqlite3.connect("file:nosuchdb.db?mode=rw", uri=True)
Traceback (most recent call last):
OperationalError: unable to open database file

Create a shared named in-memory database:

db = "file:mem1?mode=memory&cache=shared"
con1 = sqlite3.connect(db, uri=True)
con2 = sqlite3.connect(db, uri=True)
with con1:
    con1.execute("CREATE TABLE shared(data)")
    con1.execute("INSERT INTO shared VALUES(28)")
res = con2.execute("SELECT data FROM shared")
assert res.fetchone() == (28,)

More information about this feature, including a list of parameters, can be found in the SQLite URI documentation.

How to create and use row factories¶

By default, sqlite3 represents each row as a tuple. If a tuple does not suit your needs, you can use the sqlite3.Row class or a custom row_factory.

While row_factory exists as an attribute both on the Cursor and the Connection, it is recommended to set Connection.row_factory, so all cursors created from the connection will use the same row factory.

Row provides indexed and case-insensitive named access to columns, with minimal memory overhead and performance impact over a tuple. To use Row as a row factory, assign it to the row_factory attribute:

>>> con = sqlite3.connect(":memory:")
>>> con.row_factory = sqlite3.Row

Queries now return Row objects:

>>> res = con.execute("SELECT 'Earth' AS name, 6378 AS radius")
>>> row = res.fetchone()
>>> row.keys()
['name', 'radius']
>>> row[0]         # Access by index.
'Earth'
>>> row["name"]    # Access by name.
'Earth'
>>> row["RADIUS"]  # Column names are case-insensitive.
6378

Примітка

The FROM clause can be omitted in the SELECT statement, as in the above example. In such cases, SQLite returns a single row with columns defined by expressions, e.g. literals, with the given aliases expr AS alias.

You can create a custom row_factory that returns each row as a dict, with column names mapped to values:

def dict_factory(cursor, row):
    fields = [column[0] for column in cursor.description]
    return {key: value for key, value in zip(fields, row)}

Using it, queries now return a dict instead of a tuple:

>>> con = sqlite3.connect(":memory:")
>>> con.row_factory = dict_factory
>>> for row in con.execute("SELECT 1 AS a, 2 AS b"):
...     print(row)
{'a': 1, 'b': 2}

The following row factory returns a named tuple:

from collections import namedtuple

def namedtuple_factory(cursor, row):
    fields = [column[0] for column in cursor.description]
    cls = namedtuple("Row", fields)
    return cls._make(row)

namedtuple_factory() can be used as follows:

>>> con = sqlite3.connect(":memory:")
>>> con.row_factory = namedtuple_factory
>>> cur = con.execute("SELECT 1 AS a, 2 AS b")
>>> row = cur.fetchone()
>>> row
Row(a=1, b=2)
>>> row[0]  # Indexed access.
1
>>> row.b   # Attribute access.
2

With some adjustments, the above recipe can be adapted to use a dataclass, or any other custom class, instead of a namedtuple.

How to handle non-UTF-8 text encodings¶

By default, sqlite3 uses str to adapt SQLite values with the TEXT data type. This works well for UTF-8 encoded text, but it might fail for other encodings and invalid UTF-8. You can use a custom text_factory to handle such cases.

Because of SQLite’s flexible typing, it is not uncommon to encounter table columns with the TEXT data type containing non-UTF-8 encodings, or even arbitrary data. To demonstrate, let’s assume we have a database with ISO-8859-2 (Latin-2) encoded text, for example a table of Czech-English dictionary entries. Assuming we now have a Connection instance con connected to this database, we can decode the Latin-2 encoded text using this text_factory:

con.text_factory = lambda data: str(data, encoding="latin2")

For invalid UTF-8 or arbitrary data in stored in TEXT table columns, you can use the following technique, borrowed from the Юнікод HOWTO:

con.text_factory = lambda data: str(data, errors="surrogateescape")

Примітка

The sqlite3 module API does not support strings containing surrogates.

Дивись також

Юнікод HOWTO

Пояснення¶

Transaction control¶

The sqlite3 module does not adhere to the transaction handling recommended by PEP 249.

If the connection attribute isolation_level is not None, new transactions are implicitly opened before execute() and executemany() executes INSERT, UPDATE, DELETE, or REPLACE statements; for other statements, no implicit transaction handling is performed. Use the commit() and rollback() methods to respectively commit and roll back pending transactions. You can choose the underlying SQLite transaction behaviour — that is, whether and what type of BEGIN statements sqlite3 implicitly executes – via the isolation_level attribute.

If isolation_level is set to None, no transactions are implicitly opened at all. This leaves the underlying SQLite library in autocommit mode, but also allows the user to perform their own transaction handling using explicit SQL statements. The underlying SQLite library autocommit mode can be queried using the in_transaction attribute.

The executescript() method implicitly commits any pending transaction before execution of the given SQL script, regardless of the value of isolation_level.

Змінено в версії 3.6: sqlite3 used to implicitly commit an open transaction before DDL statements. This is no longer the case.

`sqlite3` — DB-API 2.0 interface for SQLite databases¶

Підручник¶

Посилання¶

Module functions¶

Module constants¶

Connection objects¶

Cursor objects¶

Row objects¶

Blob objects¶

PrepareProtocol objects¶

Винятки¶

Типи SQLite і Python¶

Default adapters and converters¶

How-to guides¶

How to use placeholders to bind values in SQL queries¶

How to adapt custom Python types to SQLite values¶

How to write adaptable objects¶

How to register adapter callables¶

How to convert SQLite values to custom Python types¶

Adapter and converter recipes¶

How to use connection shortcut methods¶

How to use the connection context manager¶

How to work with SQLite URIs¶

How to create and use row factories¶

How to handle non-UTF-8 text encodings¶

Пояснення¶

Transaction control¶

Table of Contents

Попередній розділ

Наступна тема

Ця сторінка

sqlite3 — DB-API 2.0 interface for SQLite databases¶

Підручник¶

Посилання¶

Module functions¶

Module constants¶

Connection objects¶

Cursor objects¶

Row objects¶

Blob objects¶

PrepareProtocol objects¶

Винятки¶

Типи SQLite і Python¶

Default adapters and converters¶

How-to guides¶

How to use placeholders to bind values in SQL queries¶

How to adapt custom Python types to SQLite values¶

How to write adaptable objects¶

How to register adapter callables¶

How to convert SQLite values to custom Python types¶

Adapter and converter recipes¶

How to use connection shortcut methods¶

How to use the connection context manager¶

How to work with SQLite URIs¶

How to create and use row factories¶

How to handle non-UTF-8 text encodings¶

Пояснення¶

Transaction control¶

`sqlite3` — DB-API 2.0 interface for SQLite databases¶