Python Data Access 简明教程
Python SQLite - Introduction
Installation
SQLite3 可以使用 sqlite3 模块与 Python 集成,该模块由 Gerhard Haring 编写。它提供与 PEP 249 描述的 DB-API 2.0 规范兼容的 SQL 接口。您无需单独安装此模块,因为它默认随 Python 2.5.x 及更高版本一起提供。
SQLite3 can be integrated with Python using sqlite3 module, which was written by Gerhard Haring. It provides an SQL interface compliant with the DB-API 2.0 specification described by PEP 249. You do not need to install this module separately because it is shipped by default along with Python version 2.5.x onwards.
要使用 sqlite3 模块,您必须首先创建一个表示数据库的连接对象,然后可以选择创建一个游标对象,它将帮助您执行所有 SQL 语句。
To use sqlite3 module, you must first create a connection object that represents the database and then optionally you can create a cursor object, which will help you in executing all the SQL statements.
Python sqlite3 module APIs
以下是重要的 sqlite3 模块例程,它可以满足您使用 Python 程序处理 SQLite 数据库的要求。如果您正在寻找更复杂的应用程序,则可以查看 Python sqlite3 模块的官方文档。
Following are important sqlite3 module routines, which can suffice your requirement to work with SQLite database from your Python program. If you are looking for a more sophisticated application, then you can look into Python sqlite3 module’s official documentation.
Sr.No. |
API & Description |
1 |
sqlite3.connect(database [,timeout ,other optional arguments]) This API opens a connection to the SQLite database file. You can use ":memory:" to open a database connection to a database that resides in RAM instead of on disk. If database is opened successfully, it returns a connection object. |
2 |
connection.cursor([cursorClass]) This routine creates a cursor which will be used throughout your database programming with Python. This method accepts a single optional parameter cursorClass. If supplied, this must be a custom cursor class that extends sqlite3.Cursor. |
3 |
cursor.execute(sql [, optional parameters]) This routine executes an SQL statement. The SQL statement may be parameterized (i. e. placeholders instead of SQL literals). The sqlite3 module supports two kinds of placeholders: question marks and named placeholders (named style). For example − cursor.execute("insert into people values (?, ?)", (who, age)) |
4 |
connection.execute(sql [, optional parameters]) This routine is a shortcut of the above execute method provided by the cursor object and it creates an intermediate cursor object by calling the cursor method, then calls the cursor’s execute method with the parameters given. |
5 |
cursor.executemany(sql, seq_of_parameters) This routine executes an SQL command against all parameter sequences or mappings found in the sequence sql. |
6 |
connection.executemany(sql[, parameters]) This routine is a shortcut that creates an intermediate cursor object by calling the cursor method, then calls the cursor.s executemany method with the parameters given. |
7 |
cursor.executescript(sql_script) This routine executes multiple SQL statements at once provided in the form of script. It issues a COMMIT statement first, then executes the SQL script it gets as a parameter. All the SQL statements should be separated by a semi colon (;). |
8 |
connection.executescript(sql_script) This routine is a shortcut that creates an intermediate cursor object by calling the cursor method, then calls the cursor’s executescript method with the parameters given. |
9 |
connection.total_changes() This routine returns the total number of database rows that have been modified, inserted, or deleted since the database connection was opened. |
10 |
connection.commit() This method commits the current transaction. If you don’t call this method, anything you did since the last call to commit() is not visible from other database connections. |
11 |
connection.rollback() This method rolls back any changes to the database since the last call to commit(). |
12 |
connection.close() This method closes the database connection. Note that this does not automatically call commit(). If you just close your database connection without calling commit() first, your changes will be lost! |
13 |
cursor.fetchone() This method fetches the next row of a query result set, returning a single sequence, or None when no more data is available. |
14 |
cursor.fetchmany([size = cursor.arraysize]) This routine fetches the next set of rows of a query result, returning a list. An empty list is returned when no more rows are available. The method tries to fetch as many rows as indicated by the size parameter. |
15 |
cursor.fetchall() This routine fetches all (remaining) rows of a query result, returning a list. An empty list is returned when no rows are available. |