过滤和排序数据

Posted 2020-09-29 丿随缘

1.过滤：

SELECT    *|{[DISTINCT] column|expression [alias],...}
FROM    table
[WHERE    condition(s)];

2.字符：

SELECT last_name, job_id, department_id
FROM   employees
WHERE  last_name = ‘Whalen‘;

3.比较运算符：

BETWEEN...AND...（在两个值之间 (包含边界)）

SELECT last_name, salary
FROM   employees
WHERE  salary BETWEEN 2500 AND 3500;

IN(set) （等于值列表中的一个）

SELECT employee_id, last_name, salary, manager_id
FROM   employees
WHERE  manager_id IN (100, 101, 201);

LIKE（模糊查询）

SELECT    first_name
FROM     employees
WHERE    first_name LIKE ‘S%‘;

IS NULL（空值）

SELECT last_name, manager_id
FROM   employees
WHERE  manager_id IS NULL;

4.逻辑运算：

AND（逻辑并）

SELECT employee_id, last_name, job_id, salary
FROM   employees
WHERE  salary >=10000
AND    job_id LIKE ‘%MAN%‘;

OR（逻辑或）

SELECT employee_id, last_name, job_id, salary
FROM   employees
WHERE  salary >= 10000
OR     job_id LIKE ‘%MAN%‘;

NOT（逻辑否）

SELECT last_name, job_id
FROM   emp
WHERE  job_id 
       NOT IN (‘IT_PROG‘, ‘ST_CLERK‘, ‘SA_REP‘);

5.ORDER BY子句

使用 ORDER BY 子句排序 。

ASC: 升序

SELECT   last_name, job_id, department_id, hire_date
FROM     employees
ORDER BY hire_date ASC ;

 

 

DESC: 降序

SELECT   last_name, job_id, department_id, hire_date
FROM     employees
ORDER BY hire_date DESC ;

 

SELECT   last_name, job_id, department_id, hire_date
FROM     employees
ORDER BY hire_date ;