Mysql：数据操作_增删改查

Posted 2020-11-20 jxba

数据操作

插入数据

insert into test (id,email,ip,state) values(2,‘[email protected]‘,‘127.0.0.1‘,‘0‘);

删除数据

delete from test where id = 1;

修改数据

update test set id=‘1‘,email=‘[email protected]‘ where id=1;

查数据

select * from test;                          取所有数据

select * from test by id limit 0,2;        取前两条数据

select * from test where email like ‘_q%‘ 查含有q字符 _表示一个 %表示多个

select * from test order by id asc;        降序desc

select * from test id not in(‘2‘,‘3‘);     id不含2,3或者去掉not表示含有

select * from test timer between 1 and 10; 数据在1,10之间

修改表中数据update

语法：update 表名 set 字段=新值,… where 条件

mysql> update MyClass set name=‘Mary‘ where id=1;

子查询

(表名1：aa 表名2：bb) 
select a,b,c from aa where a IN (select d from bb ) 或者:

select a,b,c from aa where a IN (1,2,3) 

选择从10到15的记录 

select top 5 * from (select top 15 * from table order by id asc) table_别名 order by id desc 

在线视图查询

(表名1：aa ) 
select * from (select a,b,c FROM aa) t where t.a > 1; 

连接join on

内连接

#等值连接又叫内链接 inner join 只返回两个表中连接字段相等的行

select * from A inner join B on A.id = B.id; #写法1

select * from A,B where A.id = B.id; #写法2

select a.id,a.title from A a inner join B b on a.id=b.id and a.id=1;#写法3 表的临时名称

select a.id as ID,a.title as 标题 from A inner join B on A.id=B.id;#添加as字句

 

左连接

#左连接又叫外连接 left join 返回左表中所有记录和右表中连接字段相等的记录

select * from A left join B on A.id = B.id;

 

select * from A left join (B,C,D) on (B.i1=A.i1 and C.i2=A.i2 and D.i3 = A.i3);#复杂连接

右连接

#右连接又叫外连接 right join 返回右表中所有记录和左表中连接字段相等的记录

select * from A right join B on A.id = B.id;

 

完整连接

#完整外部链接 full join 返回左右表中所有数据

select * from A full join B on A.id = B.id;

 

交叉连接

#交叉连接 没有where字句 返回卡迪尔积

select * from A cross join B;