Python PyMySQL：切换数据库

#Python PyMySQL

我们以查询某个库下所有的表为例。

方式1

先创建数据库连接，然后使用 use dbname 选择数据库。

import pymysql

conn = pymysql.connect(host='127.0.0.1',
                       user='root',
                       password='123456',
                       port=3306)
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)
cursor.execute('use information_schema;')
cursor.execute('show tables;')

for item in cursor.fetchall():
    print(type(item), item)

cursor.close()
conn.close()

运行结果示例（省略部分内容）：

<class 'dict'> {'Tables_in_information_schema': 'CHARACTER_SETS'}
<class 'dict'> {'Tables_in_information_schema': 'COLLATIONS'}
<class 'dict'> {'Tables_in_information_schema': 'COLLATION_CHARACTER_SET_APPLICABILITY'}
<class 'dict'> {'Tables_in_information_schema': 'COLUMNS'}
<class 'dict'> {'Tables_in_information_schema': 'COLUMN_PRIVILEGES'}
<class 'dict'> {'Tables_in_information_schema': 'ENGINES'}
<class 'dict'> {'Tables_in_information_schema': 'EVENTS'}
<class 'dict'> {'Tables_in_information_schema': 'FILES'}
<class 'dict'> {'Tables_in_information_schema': 'GLOBAL_STATUS'}
<class 'dict'> {'Tables_in_information_schema': 'GLOBAL_VARIABLES'}

方式2

连接时指定数据库：

import pymysql

conn = pymysql.connect(host='127.0.0.1',
                       user='root',
                       password='123456',
                       port=3306,
                       database='information_schema')   # 指定数据库
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)
cursor.execute('show tables;')

for item in cursor.fetchall():
    print(type(item), item)

cursor.close()
conn.close()

( 本文完 )