语法

SELECT 字段列表 FROM 表名 WHERE 条件列表;

条件

示例

--1
select * from emp where age = 88;
--2
select * from emp where age < 20;
--3
select * from emp where age <= 20;
--4
select * from emp where idcard is null;
--5
select * from emp where idcard is not null;
--6
select * from emp where age != 88;
select * from emp where age <> 88;
--7
select * from emp where age >= 15 && age <= 20;
select * from emp where age >= 15 and age <= 20;
select * from emp where age between 15 and 20;
--8
select * from emp where gender = '女' and age < 25;
--9 //注意
select * from emp where age = 18 or age = 20 or age = 40;
select * from emp where age in(18,20,40);
--10 //注意
select * from emp where name like '__';  /*2位下划线*/
--11 查询身份证号最后一位是X的员工信息 //注意
select * from emp where idcard like '%X';
select * from emp where idcard like '_________________X'; /*17位下划线*/