数据库 增删改查 简单操作

//查询

select * from table1；

select * from table1 where id = 2 and name year = 18 and devid = 5;   //显示全部信息

select id, year, devid from table1;                      //显示year devid id 3项

select * from(select * from table1 where devid = 4 and year = 17 order by id desc) as totle 

//在括号中查询到的结果中进行查询 as 是为这个查询结果起一个新的名字totle 

select * from(select * from table1 where devid = 4 and year = 17 order by id desc) as totle  limit 1

//在括号中查询到的结果中进行查询 as 是为这个查询结果起一个新的名字totle  显示1行

//删除

delete from table1 where id = 5 order by year desc limit 3;  // id 等于5的所有行 每次删除3行 按照year 降序排列的顺序

//插入

insert into table1 （id,devid,year）values(10,12,19) ;//插入数据 

//更新

update table1 set  id=10 where year = 18;  //更新year 为18的 id为10；