0428作业＋代码＋知识点总结

USE ee200402;
CREATE TABLE student(
	id INT,   -- id编号
	NAME VARCHAR(20), -- 姓名
	chinese INT,  -- 语文
	english INT, -- 英语
	math INT -- 数学
);
SELECT * FROM student;

INSERT INTO student(id,NAME,chinese,english,math) VALUES(1,'行哥',89,78,90);
INSERT INTO student(id,NAME,chinese,english,math) VALUES(2,'潘金莲',67,53,95);
INSERT INTO student(id,NAME,chinese,english,math) VALUES(3,'凤姐',87,78,77);
INSERT INTO student(id,NAME,chinese,english,math) VALUES(4,'旺财',88,98,92);
INSERT INTO student(id,NAME,chinese,english,math) VALUES(5,'白小黑',82,84,67);
INSERT INTO student(id,NAME,chinese,english,math) VALUES(6,'白小黄',55,85,45);
INSERT INTO student(id,NAME,chinese,english,math) VALUES(7,'范蹦蹦',75,65,30);

SELECT * FROM student;

SELECT 
NAME,
english
 FROM student;
 
 SELECT DISTINCT
 chinese,
 english
 FROM student;
 
 SELECT
 NAME,
(chinese+english+math)
AS total
 FROM student;
 
  SELECT
 NAME,
 (chinese+english+math)
AS "总分",
(chinese+english+math+10)
AS "加了特长分"
 FROM student;

SELECT
student.`id` ,
student.`name` ,
(chinese+english+math)
AS "总分"
FROM student
WHERE id = '1';

SELECT
*
FROM
student
WHERE english>90;

SELECT
*
FROM 
student
WHERE english>=80 && english<=90;

SELECT
*
FROM
student
WHERE math IN (89,90,91);

SELECT
*
FROM
student
WHERE NAME LIKE "%白%";

SELECT
*
FROM
student
WHERE math >80 AND chinese > 80;

SELECT
*
FROM
student
ORDER BY
math ASC;



-- 16.对总分降序排序，然后再按数学从高到低的顺序输出

SELECT
student.`name` ,
student.`math` ,

(chinese+english+math)
AS "总分"
FROM student
ORDER BY 总分 DESC,math ASC;

-- 17.对姓白的学生成绩排序输出(排序规则自己定义)

SELECT
student.`name` ,
student.`math` ,
student.`chinese` ,
student.`english` ,
(chinese+english+math)
AS "总分"
FROM student
WHERE NAME LIKE "%白%"
ORDER BY 总分 DESC,math ASC;

-- 18.查询数学成绩大于等于平均分的所有学生信息

SELECT
student.`name` ,
student.`math`,
AVG(MATH) AS "av"
FROM
student
WHERE math > 'av';

-- 19.查询出英语成绩最高分的学生信息
SELECT
student.`name` ,
MAX(english)
FROM
student;
-- 20.模糊查询出学生姓名中第二个字是金的学生信息

SELECT
*
FROM
student
WHERE
NAME LIKE '%_金%';
-- 21.查询出英语成绩平均分是多少
SELECT
AVG(english)
AS "英语平均分"
FROM student;
-- 22.查询出数学总分是多少

SELECT
SUM(math)
AS "数学总分"
FROM student;

-- 23.查询学生表中有多少条记录
	SELECT
	COUNT(id) AS '总记录数'
	FROM
	student;