如何在python中转储单个sqlite3表?

I would like to dump only one table but by the looks of it there is no parameter for this.

我想只转储一个表，但是根据它的外观，没有参数。

I found this example of the dump but is is for all tables:

我发现了这个转储的示例，但对于所有表都是这样的:

# Convert file existing_db.db to SQL dump file dump.sql
import sqlite3, os

con = sqlite3.connect('existing_db.db')
with open('dump.sql', 'w') as f:
    for line in con.iterdump():
        f.write('%s\n' % line)

3 个解决方案

#1

You can copy only the single table in an in memory db:

您只能在内存db中复制单个表:

import sqlite3

def getTableDump(db_file, table_to_dump):
    conn = sqlite3.connect(':memory:')    
    cu = conn.cursor()
    cu.execute("attach database '" + db_file + "' as attached_db")
    cu.execute("select sql from attached_db.sqlite_master "
               "where type='table' and name='" + table_to_dump + "'")
    sql_create_table = cu.fetchone()[0]
    cu.execute(sql_create_table);
    cu.execute("insert into " + table_to_dump +
               " select * from attached_db." + table_to_dump)
    conn.commit()
    cu.execute("detach database attached_db")
    return "\n".join(conn.iterdump())

TABLE_TO_DUMP = 'table_to_dump'
DB_FILE = 'db_file'

print getTableDump(DB_FILE, TABLE_TO_DUMP)

Pro: Simplicity and reliability: you don't have to re-write any library method, and you are more assured that the code is compatible with future versions of the sqlite3 module.

优点:简单和可靠:您不需要重写任何库方法，而且您更确信代码与sqlite3模块的未来版本兼容。

Con: You need to load the whole table in memory, which may or may not be a big deal depending on how big the table is, and how much memory is available.

Con:您需要在内存中加载整个表，这取决于表的大小，以及可用的内存大小。

#2

Dump realization lies here http://coverage.livinglogic.de/Lib/sqlite3/dump.py.html (local path: PythonPath/Lib/sqlite3/dump.py)

Dump实现位于这里，http://coverage.livinglogic.de/lib/sqlite3 / Dump .html(本地路径:PythonPath/Lib/sqlite3/ Dump .py)

You can modify it a little:

你可以稍微修改一下:

# Mimic the sqlite3 console shell's .dump command
# Author: Paul Kippes <[e-mail]>

def _iterdump(connection, table_name):
    """
    Returns an iterator to the dump of the database in an SQL text format.

    Used to produce an SQL dump of the database.  Useful to save an in-memory
    database for later restoration.  This function should not be called
    directly but instead called from the Connection method, iterdump().
    """

    cu = connection.cursor()
    table_name = table_name

    yield('BEGIN TRANSACTION;')

    # sqlite_master table contains the SQL CREATE statements for the database.
    q = """
       SELECT name, type, sql
        FROM sqlite_master
            WHERE sql NOT NULL AND
            type == 'table' AND
            name == :table_name
        """
    schema_res = cu.execute(q, {'table_name': table_name})
    for table_name, type, sql in schema_res.fetchall():
        if table_name == 'sqlite_sequence':
            yield('DELETE FROM sqlite_sequence;')
        elif table_name == 'sqlite_stat1':
            yield('ANALYZE sqlite_master;')
        elif table_name.startswith('sqlite_'):
            continue
        else:
            yield('%s;' % sql)

        # Build the insert statement for each row of the current table
        res = cu.execute("PRAGMA table_info('%s')" % table_name)
        column_names = [str(table_info[1]) for table_info in res.fetchall()]
        q = "SELECT 'INSERT INTO \"%(tbl_name)s\" VALUES("
        q += ",".join(["'||quote(" + col + ")||'" for col in column_names])
        q += ")' FROM '%(tbl_name)s'"
        query_res = cu.execute(q % {'tbl_name': table_name})
        for row in query_res:
            yield("%s;" % row[0])

    # Now when the type is 'index', 'trigger', or 'view'
    #q = """
    #    SELECT name, type, sql
    #    FROM sqlite_master
    #        WHERE sql NOT NULL AND
    #        type IN ('index', 'trigger', 'view')
    #    """
    #schema_res = cu.execute(q)
    #for name, type, sql in schema_res.fetchall():
    #    yield('%s;' % sql)

    yield('COMMIT;')

Now it accepts table name as second argument.
You can use it like this:

现在它接受表名作为第二个参数。你可以这样使用:

with open('dump.sql', 'w') as f:
    for line in _iterdump(con, 'GTS_vehicle'):
        f.write('%s\n' % line)

Will get something like:

会得到类似:

BEGIN TRANSACTION;
CREATE TABLE "GTS_vehicle" ("id" integer NOT NULL PRIMARY KEY, "name" varchar(20) NOT NULL, "company_id" integer NULL, "license_plate" varchar(20) NULL, "icon" varchar(100) NOT NULL DEFAULT 'baseicon.png', "car_brand" varchar(30) NULL, "content_type_id" integer NULL, "modemID" varchar(100) NULL, "distance" integer NULL, "max_speed" integer NULL DEFAULT 100, "max_rpm" integer NULL DEFAULT 4000, "fuel_tank_volume" integer NULL DEFAULT 70, "max_battery_voltage" integer NULL, "creation_date" datetime NOT NULL, "last_RFID" text NULL);
INSERT INTO "GTS_vehicle" VALUES(1,'lan1_op1_car1',1,'03115','baseicon.png','UFP',16,'lan_op1_car1',NULL,100,4000,70,12,'2011-06-23 11:54:32.395000',NULL);
INSERT INTO "GTS_vehicle" VALUES(2,'lang_op1_car2',1,'03','baseicon.png','ыва',16,'lan_op1_car2',NULL,100,4000,70,12,'2011-06-23 11:55:02.372000',NULL);
INSERT INTO "GTS_vehicle" VALUES(3,'lang_sup_car1',1,'0000','baseicon.png','Fiat',16,'lan_sup_car1',NULL,100,4000,70,12,'2011-06-23 12:32:09.017000',NULL);
INSERT INTO "GTS_vehicle" VALUES(4,'lang_sup_car2',1,'123','baseicon.png','ЗАЗ',16,'lan_sup_car2',NULL,100,4000,70,12,'2011-06-23 12:31:38.108000',NULL);
INSERT INTO "GTS_vehicle" VALUES(9,'lang_op2_car1',1,'','baseicon.png','',16,'1233211234',NULL,100,4000,70,12,'2011-07-05 13:32:09.865000',NULL);
INSERT INTO "GTS_vehicle" VALUES(11,'Big RIder',1,'','baseicon.png','0311523',16,'111',NULL,100,4000,70,20,'2011-07-07 12:12:40.358000',NULL);
COMMIT;

#3

By iterdump(), all information would be displayed like this:

通过iterdump()，所有的信息都将显示如下:

INSERT INTO "name" VALUES(1, 'John')
INSERT INTO "name" VALUES(2, 'Jane')
INSERT INTO "phone" VALUES(1, '111000')
INSERT INTO "phone" VALUES(2, '111001')

An easy way is by filter certain keywords by string.startswith() method. For example, the table name is 'phone':

一种简单的方法是通过string.startswith()方法过滤某些关键字。例如，表名是“phone”:

# Convert file existing_db.db to SQL dump file dump.sql
import sqlite3, os

con = sqlite3.connect('existing_db.db')
with open('dump.sql', 'w') as f:
    for line in con.iterdump():
        if line.startswith('INSERT INTO "phone"'):
            f.write('%s\n' % line)

Not very smart, but can fit your objective.

不是很聪明，但能符合你的目标。