【数据库-MySql】常用查询

1、比较两个表字段差异

db1：数据库1；

db2：数据块2；

tb1：为db1与db2共同名称的数据库。

SELECT
	*
FROM
	information_schema.`COLUMNS`
WHERE
	TABLE_SCHEMA IN ('db1', 'db2')
AND
	TABLE_NAME = 'tb1' ORDER BY COLUMN_NAME

2、将数据的日期更新到当前日期

UPDATE tb1
SET time1 = CONCAT(
	DATE_FORMAT(NOW(), '%Y-%m-%d'),
	DATE_FORMAT(time1, ' %H:%i:%S')
),
 time2 = CONCAT(
	DATE_FORMAT(NOW(), '%Y-%m-%d'),
	DATE_FORMAT(time2,' %H:%i:%S')
)
LIMIT 520;

3、清空所有表的数据

db1：数据库名称

SELECT
	CONCAT("DELETE FROM db1.`",TABLE_NAME,"`;")
FROM
	information_schema.`TABLES`
WHERE
	TABLE_SCHEMA = 'db1'
AND
	TABLE_TYPE = 'BASE TABLE';

4、删除所有表

db1：数据库名称

SELECT 
    CONCAT("DROP TABLE `",TABLE_NAME,"`;") 
FROM 
    information_schema.`TABLES` 
WHERE 
    TABLE_TYPE = "BASE TABLE" 
AND 
    TABLE_SCHEMA = "db1";

5、删除所有视图

db1：数据库名称

SELECT 
    CONCAT("DROP VIEW `",TABLE_NAME,"`;")  
FROM 
    information_schema.`TABLES` 
WHERE 
    TABLE_TYPE = "VIEW" 
AND 
    TABLE_SCHEMA = "db1";

6、删除所有函数

db1：数据库名称

SELECT 
    CONCAT("DROP FUNCTION `",ROUTINE_NAME,"`;")  
FROM 
    information_schema.ROUTINES 
WHERE  
    ROUTINE_TYPE = "FUNCTION" 
AND 
    ROUTINE_SCHEMA = "db1";

7、删除所有存储过程

db1：数据库名称

SELECT 
    CONCAT("DROP PROCEDURE `",ROUTINE_NAME,"`;")  
FROM 
    information_schema.ROUTINES 
WHERE  
    ROUTINE_TYPE = "PROCEDURE" 
AND 
    ROUTINE_SCHEMA = "db1";