1.查看MySQL版本
sql
select version();
2.快速复制表结构,不包含相关主键及约束
sql
create table user_test as select * from user where 1=2;
3.uuid
sql
select uuid(),uuid_short();
4.替换uuid()里的'-'为''
sql
select replace(uuid(),'-','');
5.md5摘要
sql
select md5(uuid()),md5('123456');
6.复制数据
sql
insert into user_test(id, name, age, city)
select replace(uuid(),'-',''),name,age,'vue3' from user;
insert into user_test(id, name, age, city)
select md5(uuid()),name,25,city from user;
7.ip4地址转整数,整数转换ip4地址
sql
select INET_ATON('127.0.0.1') address_2_number,
INET_NTOA(2130706433) number_2_address;
8.删除数据,不允许边查询边删除/更新。
sql
delete from user_test where id in (select id from user_test where parent_id='75e2f86d0a2c11ee89c70242ac110002');
-- [HYO00][1093] You can't specify target table 'user_test' for update in FROM clause
delete from user_test where id in (select id from (select id from user_test where parent_id='75e2f86d0a2c11ee89c70242ac110002') t);
9.查询数据库blob字段
sql
select convert(remark using utf8) from user
10.关联查询,没有数据的统计为0,构造基础数据,子查询或连接查询实现
sql
select l.province,ifnull(
(select biz.num from (
select '北京' as province,100 as num
union all
select '深圳' as province,208 as num
) biz where biz.province = l.province),0) as num
from (select '北京' as province
union all
select '上海'
union all
select '广州'
union all
select '深圳') l