1,增
insert into 表 (列名,列名...) values (值,值,值...) insert into 表 (列名,列名...) values (值,值,值...),(值,值,值...) insert into 表 (列名,列名...) select (列名,列名...) from 表2,删
delete from 表 delete from 表 where id=1 and name='tom'3,改
update 表 set name = 'tom' where id>14,查
select * from 表 select * from 表 where id > 1 select nid,name,gender as gg from 表 where id > 15,其他
a、条件 select * from 表 where id > 1 and name != 'tom' and num = 12; select * from 表 where id between 5 and 16; select * from 表 where id in (11,22,33) select * from 表 where id not in (11,22,33) select * from 表 where id in (select nid from 表) b、通配符 select * from 表 where name like 'tom%' - tom开头的所有(多个字符串) select * from 表 where name like 'tom_' - tom开头的所有(一个字符) c、限制 select * from 表 limit 5; - 前5行 select * from 表 limit 4,5; - 从第4行开始的5行 select * from 表 limit 5 offset 4 - 从第4行开始的5行 d、排序 select * from 表 order by 列 asc - 根据 “列” 从小到大排列 select * from 表 order by 列 desc - 根据 “列” 从大到小排列 select * from 表 order by 列1 desc,列2 asc - 根据 “列1” 从大到小排列,如果相同则按列2从小到大排序 e、分组 select num from 表 group by num select num,nid from 表 group by num,nid select num,nid from 表 where nid > 10 group by num,nid order nid desc select num,nid,count(*),sum(score),max(score),min(score) from 表 group by num,nid f、连表 无对应关系则不显示 select A.num, A.name, B.name from A,B Where A.nid = B.nid 无对应关系则不显示 select A.num, A.name, B.name from A inner join B on A.nid = B.nid A表所有显示,如果B中无对应关系,则值为null select A.num, A.name, B.name from A left join B on A.nid = B.nid B表所有显示,如果B中无对应关系,则值为null select A.num, A.name, B.name from A right join B on A.nid = B.nid g.组合 组合,自动处理重合 select nickname from A union select name from B 组合,不处理重合 select nickname from A union all select name from B h,统计 count(x) select count(*) from student /计算所有记录的个数 select count(age) from student /计算age有值的记录个数(Null不计算在内) avg(x) /计算某个字段的平均值 sum(x) /计算某个字段的总和 max(x) /计算某个字段的最大值 min(x) /计算某个字段的最小值