sql简单语法
1、insert
insert into tb_shop (shop_id,shop_name,shop_num,shop_create_time) values(default,'奉先茶馆',32,'2019-07-25 19:30:23')
2、delete
delete from tb_shop
3、update
update tb_shop set shop_name='子龙面馆',shop_num=76
4、select
select * from tb_shop select shop_id,shop_name from tb_shop
5、count
汇总行数,即数据条数
select count(*) from tb_shop
6、sum()
汇总字段的值
select sum(shop_num) from tb_shop
sum( if(xxx ) )
select sum(if(a>60), 1,0) AS aaa from tb_A
如果a>60,则将1累加到aaa,否在将0累加到aaa;1,0可以用某个字段代替,表示某个字段的值。
7、concat()
将多个字符串连接成一个字符串。
返回结果为连接参数产生的字符串,如果有任何一个参数为null,则返回值为null。
select count(id,',',name) from tb_shop
结果:2,小汪 如果没用加 ',' 则是:2小汪。