Docs/数据库/sql基础.md

1. 创建表

create table ttt(
    no int primary key,
    name char(10) not null,
    depno int,
    indate date,
    sal numeric(8,2)
);
// numrtic(a,b): 数字类型，总位数为8，小数点后b位
// char(a): 定长为a的字符串
// varchar(a): 变长字符串，最大长度为a

2. 删除表

drop table ttt;
drop table ttt if exists;

3. 插入

insert into ttt values(1,"ttt",1,"2023-05-28",12.33);
insert into ttt(no,name,depno,indate,sal) values(1,"ttt",1,"2023-05-28",12.33);
insert into ttt(no,name,depno) values(1,"ttt",1);

4. distinct去除重复

selet distinct depno from ttt;

5.查询多个值

select name from ttt where depno in (2,3,5);
select name from ttt where depno not in (2,3,5);

6. between

select name from ttt where indate between '2022-01-22' and '2023-04-30';
// 等价
select name from ttt where indate>='2022-01-22' and indate<>='2023-04-30';

select name from ttt where indate not between '2022-01-22' and '2023-04-30';