- 创建表
create table people(id int(11),name char(11),phone char
(20),pwd varchar(40));
2. 增加语句
insert into people values(9,'gang',13023299931,'qwert');
3.向特定列增加语句
insert into people(id,name,phone ) values(9,'gang',13023299931);
4.删除表全部内容
delete from people；
5.删除某行数据
delete from people where id =9（字符要加引号）
6.查询数据
select * from people
select name,phone from people where id =5
7.更新表中的某个或者某几个数据
update people set phone ='12345',name ='gangjian' where id =5
8.双表连接查询
首先新建两张表分别为男女朋友用户信息表
create table userman (id int (10) primary key auto_increment ,age int (10),name varchar (40));
insert into userman (age,name)values (23,'wq'),(24,'er'),(25,'ty'),(26,'sd'),(27,'cv'),(28,'cz'),(29,'sv');
create table userwoman (id int (10) primary key auto_increment, use_id int(10), age int (10),name varchar (40));
insert into userwoman (use_id, age, name)values (2,23,'fff'),(4,25,'hhhhh'),(6,26,'llll');
需求：1.筛选出所有有对象的用户信息
等值连接
select * from userman,userwoman where userman.id = userwoman.use_id;
select * from userman join userwoman on userman.id = userwoman.use_id;
select * from userman inner join userwoman on userman.id = userwoman.use_id;
select * from userman cross join userwoman on userman.id = userwoman.use_id;
筛选出所有人的对象信息
左连接：
select * from userman left join userwoman on userman.id = userwoman.use_id;
右连接
select * from userwoman right join userman on userman.id = userwoman.use_id;
- 筛选出没有对象的信息
select * from userman left join userwoman on userman.id = userwoman.use_id where userwoman.use_id is null;
