[分享]软件5班_排序与分页

SELECT * from employees;

SELECT employee_id,salary
from employees;

-- 排序用到ORDER BY

-- 只用ORDER BY 默认是升序

SELECT employee_id,last_name,salary
from employees
ORDER BY salary;

-- DESC 降序

SELECT employee_id,last_name,salary
from employees
ORDER BY salary DESC;

-- ASC 升序

SELECT employee_id,last_name,salary
from employees
ORDER BY salary ASC;

SELECT employee_id,salary*12 year_salary
from employees;

-- 列别名不能在where里使用

SELECT employee_id,salary*12 year_salary
from employees
where year_salary > 50000;

-- 列别名能在ORDER BY 使用

SELECT employee_id,salary*12 year_salary
from employees
ORDER BY year_salary DESC;

SELECT employee_id,salary*12 year_salary
from employees
ORDER BY year_salary;

SELECT employee_id,salary
from employees
where salary > 6000
ORDER BY salary DESC;

SELECT employee_id,salary sal
from employees
where sal > 6000
ORDER BY sal DESC;


SELECT employee_id,salary,department_id
FROM employees
ORDER BY department_id ,salary ,,,,,,;

SELECT employee_id,salary
FROM employees;

-- 第一页
SELECT employee_id,salary
FROM employees
LIMIT 0,10;

SELECT employee_id,salary
FROM employees
LIMIT 10;

-- 第二页 第11条到第20条

SELECT employee_id,salary
FROM employees
LIMIT 10,10

-- 第三页 第21条到第30条

SELECT employee_id,salary
FROM employees
LIMIT 20,10;


SELECT employee_id,salary
FROM employees
LIMIT 10 OFFSET 20;



-- 第5条到第12条

SELECT employee_id,salary
FROM employees
LIMIT 4,8;





/*
第一页 (1-1)*10,10    0,10

第二页 (2-1)*10,10    10,10

第三页 (3-1)*10,10     20,10
*/