實用sql記錄

1.mysql建表語句

create table `user` (

`id` bigint (20) not null auto_increment comment '主鍵',
`username` varchar (50) not null comment '使用者名稱',
`password` varchar (50) not null comment '密碼',
primary key (`id`),
unique key `username` (`username`) comment '使用者名稱索引'
) engine = innodb default charset = utf8;

(1)查詢索引

show index

from
emp;

-- 查詢資料庫中所有表名 

select
table_name
from
information_schema. tables
where
table_schema = 'sql_learn'

select

d.deptno
from
dept d
where
exists (
select
null
from
emp e
where
d.deptno = e.deptno
);

show variables like '%time_zone%';

set global time_zone='+8:00';

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