mysql 2
本帖最后由 武汉13期龚婉莹 于 2022-3-29 20:46 编辑create tables
create database
select
server
cervice
desc
alter
first
after
select
desckhun;
alter table khun rename v-khun;
alter table khun change id sid int(10);
after table khun change sid id int(5) auto_increment;
alter table khun add id2 int(2);
alter table khun add (id3 int(2),id4 int(2));
alter table khun add id5 int(2) first;
alter table khun add id6 int(2) after id3;
alter table khun drop id2;
alter table khun drop id3,drop di4,drop id4;
drop table khun
insert into
;
insert into khun(id,name,class,phone,time)values(1,'vic',0101,13789964621,20220329);
0不等于null null指空的属性 0是一个值
查
select * from
select * from 表名 where 字段="条件"
select 字段 from 表名 where 字段="条件"
select 字段,字段 from 表名 where 字段="条件"
改
update user2 set phone=13145201314 where name='vic';
update user2 set phone=13145201314 where phone=13121212121;
update user2 set phone=1233333333 where id>=5;
删
delete from user where id=7;
delete from user;
drop table user;
truncate user;
单表查询
select * from user2 where name !="vic";
select * from user2 where name <>"vic";
select * from user2 where class=601 and phone=13145201314;
select * from user2 where class=601 or phone=13145251314;
select * from user2 where id>5;
select * from user2 where id>2 and id<7;
select * from user2 where id between 3 and 6;
select * from user2 where class in(601,2015);
select * from user2 where id not in (1,2,3,4);
select * from user2 where id is null;
select * from user2 where id is not null;
select * from user2 where name like "%in%";
select * from user2 where name like "v%";
select * from user2 where name like "%n";
select * from user2 where limit 1,5;
排序
从小到大 --升序
select * from user2 order by phone asc；
从达到小 --降序
select * from user2 order by phone desc；
分组
select * from user2 group by class；
select class，count(*) from user2 group by class having class is not null;
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