[英]how do i dump a single sqlite3 table in python?
I would like to dump only one table but by the looks of it, there is no parameter for this.我只想转储一张桌子,但从外观上看,没有参数。
I found this example of the dump but it is for all the tables in the DB:我找到了这个转储示例,但它适用于数据库中的所有表:
# 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)
You can copy only the single table in an in memory db:您只能复制 memory db 中的单个表:
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:简单可靠:您不必重新编写任何库方法,并且您更放心代码与 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.缺点:您需要将整个表加载到memory中,这取决于表的大小以及可用的 memory 的大小,这可能不是什么大问题。
Dump realization lies here http://coverage.livinglogic.de/Lib/sqlite3/dump.py.html (local path: PythonPath/Lib/sqlite3/dump.py) dump实现就在这里http://coverage.livinglogic.de/Lib/sqlite3/dump.py.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 <kippesp@gmail.com>
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.现在它接受表名作为第二个参数。
You can use it like this:你可以像这样使用它:
with open('dump.sql', 'w') as f:
for line in _iterdump(con, 'GTS_vehicle'):
f.write('%s\n' % line)
Will get something like:会得到类似的东西:
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;
By iterdump(), all information would be displayed like this:通过 iterdump(),所有信息将显示如下:
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.一种简单的方法是通过 string.startswith() 方法过滤某些关键字。 For example, the table name is 'phone':例如,表名是“电话”:
# 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,但可以满足您的目标。
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