MySQL(3)表操作

• 新增数据

  insert into 表名 (列名,列名,列名) values(对应列的值,对应列的值,对应列的值);
  

  insert into tb1(name,password) values('aaaa','123123');
  insert into tb1(name,password) values('aaaa','123123'),('alex','123');
  
  insert into tb1 values('aaaa','123123'),('aaaa','123'); -- 如果表中只有2列
  # 只有name，password两行
  

• 删除数据

  delete from 表名;
  delete from 表名 where 条件;
  

  delete from tb1;
  delete from tb1 where name="aaaa";
  delete from tb1 where name="aaaa" and password="123";
  delete from tb1 where id>9;
  

• 修改数据

  update 表名 set 列名=值;
  update 表名 set 列名=值 where 条件;
  

  update tb1 set name="aaaa";
  update tb1 set name="aaaa" where id=1;
  
  update tb1 set age=age+1;  -- 整型
  update tb1 set age=age+1 where id=2;
  
  update L3 set name=concat(name,"db");
  update L3 set name=concat(name,"123")  where id=2;  -- concat一个函数，可以拼接字符串
  

• 查询数据

  select * from 表名;
  select 列名,列名,列名 from 表名;
  select 列名,列名 as 别名,列名 from 表名;
  select * from 表名 where 条件;
  

  select * from tb1;
  select id,name,age from tb1;
  select id,name as N,age, from tb1;
  select id,name as N,age, 111 from tb1;
  
  select * from tb1 where id = 1;
  select * from tb1 where id > 1;
  select * from tb1 where id != 1;
  select * from tb1 where name="aaaa" and password="123";