SQL(sql)语句大全(insert、update、delete、select)

SQL(sql)语句大全

一、mysql基本指令

show databases 显示当前数据库

use mysql 使用当前数据库

show tables 显示当前数据库下的表

desc user 查看表结构

create database cd1706 创建数据库

二、创建表

create table if not exists person(
    id int not null auto_increment,
    name varchar(20),
    age int,
    primary key(id)
);

 create table chengdu1706(
       id int not null auto_increment,
       stdno int,
       name varchar(12),
       age int,
       birthday date,
       salary int,
       word varchar(20),
       primary key(id)
 );

三、增删改查

1、插入或添加数据 insert into

 insert into userinfo (id,username,password) values (1,"zuozuo","root");
 insert into userinfo (username,password) values ("mingming","abc123");
 insert into userinfo values (3,"xiaohua","qwer12");
 insert into article values (1,"mingming","abc","daydayup",now()); 
 insert into article values (4,"zuozuomu","eat","go to eat huoguo",timestamp());//表示当前时间戳 now() timestamp()  CURRENT_TIMESTAMP()

2. 修改 update set

 update userinfo set password = root123" where username = "zuozuo";
 mysql> update userinfo set  username = "zuozuomu" where id = 1 and password = "root123";
 update user set password = "abc123" where id > 3;  //批量修改 
 update 1809_user set age = age + 10 where id = 4;

3. 删除 数据

 delete from userinfo; 
 delete from userinfo where id = 1;
 drop table userinfo; 删表 //慎用
 drop database cd1706 删除数据库 //慎用
 truncate table userinfo 清空数据表  //慎用

4. 查询 select

select * from userinfo;
select username ,password from userinfo;
select * from article order by author;  //排序  默认升序 
select * from article order by id desc; //排序  降序  desc  表示降序 
select * from article order by author desc,content desc; author //降序 content 降序 
select * from person order by age desc limit 3,2;
select * from article limit 3; //限制3条数据
select * from article where author = "mingming" order by enterdate limit 1;
select * from userInfo where id > 2 limit 2;
select * from userInfo limit 1,2;
select count(*),author from article group by author; //分组查询
select min(enterdate),author from article group by author;  
select max(salary),department from emp group by department; 
select avg(salary),department from emp group by department; 
select * from emp where salary in (select max(salary) from emp group by department);
select * from emp where age in (select max(age) from emp group by department);
select * from  emp where salary in (10000,12000);  或者   
select * from emp where age in (22,28);
select * from emp where age = 22 or  age = 28;
select * from emp where age > 20 and age < 26;
select  * from person where age < 20 or  age >  30;

5、关联表查询

select * from emp , userinfo where emp.name = userinfo.username;  
select * from emp e,userinfo u where e.name = u.username; 
select * from article a ,emp e where e.name = a.author and e.age > 24 and a.id<5;
select * from article where author  = (select name from emp order by age desc limit 1);

6、模糊查询 like %%

select * from article where author like "ming%";   //开头
select * from article where author like "%zuo%";   // 包含
select * from article where author like "%hua";    //结束