一文整理MySQL常用基本命令

        MySQL常用基本操作。工作用了一段时间MySQL，整理了一下常用的基本命令。

1. 建表

CREATE TABLE IF NOT EXISTS `test` (
`col_1` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL,
`col_2` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL,
`col_3` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL,
`date` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

2. 删除表

drop table if exists test;
-- 删除多个表
drop table test1, test2, test3;

3. 修改表名

alter table table_name_1 rename table_name_2;

4. 修改列名

alter table table_name change column column_name_1 column_name_2 varchar(255);

5. 增加列

alter table table_name 
add column column_name varchar(255),
add column column_name2 varchar(255);

---- 增加列到特定位置：如添加 column_new列 到 column_4 这一列后面
alter table table_name add column column_new varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL after column_4;

---- 注意，如果想添加到第一列的话，可以用：
alter table table_name add column column_new varchar(255) not null first;

6. 删除列

alter table table_name drop column column_name; 

7. 插入数据

INSERT INTO dbname.table_name(col_1, col_2, col_3, date) 
VALUES('中国', '28177', '-2117', '20230817');

8. 删除数据

delete from table_name where date=20230731;

9. 更新数据

update table_name set col_2='12345' where col_1='中国' and date=20230731;

10. 用一个表的字段更新另一个表

UPDATE test_1 t1, test_2 t2
SET t1.col_2 = t2.col_5,
    t1.col_3 = t2.col_6
WHERE t1.date = t2.date 
AND t1.col_1 = t2.col_1;

11. 查看数据更新时间

SELECT 
    `TABLE_NAME`, `UPDATE_TIME` 
FROM 
    `information_schema`.`TABLES` 
WHERE 
    `information_schema`.`TABLES`.`TABLE_SCHEMA` = 'database_name' 
AND
    `information_schema`.`TABLES`.`TABLE_NAME` = 'table_name';

12. 数据库用户权限查询

select Host,User,Select_priv,Insert_priv,Update_priv,Delete_priv,Create_priv,Drop_priv from user;
select Host,Db,User,Select_priv,Insert_priv,Update_priv,Delete_priv,Create_priv,Drop_priv from db;