增删改查，最全面

1.增加内容
insert into info valuse (‘poo1‘,‘张三‘,1,‘n001‘,‘1989-2-3‘)
insert into info（code,name列名）valuse(‘p002‘,‘李四‘)     必包含主键
2.删除数据
delete from info                   删除表
delete from info where code=‘p002‘
3.修改数据
update info set name=‘李四‘      全部修改为李四
update info set name=‘李四‘ where code=‘p001‘ 
4.查询数据
（1）简单查询
select * from info         查询所有内容  *代表所有列
select code,name from info 查询指定列
select code as ‘代号‘,name as ‘姓名‘ from info 查询指定列且替换了列名
（2）条件查询
select * from car where code=‘c002‘  单条件
select * from car where trun         查询所有内容
select * from car where brand=‘b001‘and pawers=‘130‘   多条件查询  and并且关系
select * from car where brand=‘b001‘or pawers=‘130‘                or或者关系
(3)模糊查询
select * from car where name like‘%奥迪%‘   %代表任意多个字符   _代表一个任意的字符
（4）排序查询
select * from car order by powers asc/desc 单列排序 asc升序desce降序 默认升序，可不写asc
select * from car order by brand asc,powers desc   asc可不写  双列排序
（5）范围查询
select * from car where price>=40 and price<=60   60>=价格>=40
select * from car where price between 40 and 60   60>=价格>=40
(6）离散查询
select * from car where code in (‘c001‘,‘c003‘,‘c005‘,‘c007‘)  用来查找code里的(‘c001‘,‘c003‘,‘c005‘,‘c007‘)  如果寻找非，用not in
(7）聚合函数，统计查询
select sum(price) from car    查询car中所有价格之和  sum()求和      不可用于字符串
select count(*) from car      查询car中所有数据条数  *可替换为列名  可用于字符串
select max(price) from car    查询列最大值   可用于字符串
select min(price) from car    查询列最小值   可用于字符串 字符串null最小
select avg(price) from car    查询平均值     不可用于字符串
（8）分页查询
每页显示x条数据，现在取第n页的数据
select * from limit (n-1)*x,取多少
（9）去重查询
select distinct brand from car  去掉brand列的重复
（10）分组查询
select count(*),bround from car group by brand  分组查数量
select brand from car group by brand having count(*)>3  分组之后根据条件查询使用having，不能用where