mysql基礎查詢的使用
創建數據庫
student表格
create table student( id int PRIMARY KEY COMMENT 'id主鍵', `name` varchar(20) COMMENT '名稱', gender TINYINT(2) COMMENT '性別 1男 2女 3保密', age TINYINT UNSIGNED COMMENT '年齡', birthday date COMMENT '出生日期', createTime TIMESTAMP DEFAULT CURRENT_TIMESTAMP COMMENT '創建時間', updateTime TIMESTAMP DEFAULT CURRENT_TIMESTAMP COMMENT '更新時間' on update CURRENT_TIMESTAMP, isdel bit(1) DEFAULT 0 COMMENT '是否刪除 0未刪除 1已刪除 默認未刪除' );
成績表格score:
create table score ( id int PRIMARY KEY COMMENT 'id主鍵', sid int COMMENT '學生id', course VARCHAR(20) COMMENT '課程名稱', score DECIMAL(4,1) COMMENT '成績' );
因為下面插入數據沒默認寫id的值,所以id為自增的列。
添加自增:
alter table student MODIFY column id int auto_increment COMMENT 'id 主鍵'; alter table score MODIFY column id int auto_increment COMMENT 'id 主鍵';
初始化數據
數據下載地址:https://qyboke.lanzoue.com/iuhpB0n0rfij
score表:
student表格:
查詢學生張三的所有成績:
SELECT s.name,sc.course,sc.score from student s ,score sc where s.id = sc.sid and s.name = '李云';
查詢平均成績大于60的學生信息:
SELECT DISTINCT s.* from student s ,score sc where s.id = sc.sid and sc.score > 60;
查詢有成績的學生信息:
SELECT DISTINCT s.* FROM student s right JOIN score sc on s.id = sc.sid;
查詢不及格的學生信息:
SELECT DISTINCT s.* ,sc.course, sc.score FROM student s right JOIN score sc on s.id = sc.sid where sc.score < 60;
查詢各科成績最高分、最低分和平均分:
SELECT DISTINCT score.course, max(score) over(PARTITION by score.course) '最高分', min(score) over(PARTITION by score.course) '最低分', avg(score) over(PARTITION by score.course) '平均分' FROM score
查詢各科成績第一名的記錄:
SELECT DISTINCT sc.course, max(score) over(PARTITION by sc.course) '最高分' FROM score sc left JOIN student s on sc.sid = s.id
查詢男生、女生人數:
SELECT DISTINCT student.gender, count(student.gender) over(PARTITION by student.gender) from student
查詢 1990 年出生的學生名單:
SELECT * from student where YEAR(birthday) = 1990;
查詢平均成績大于等于 70 的所有學生的姓名、出生日期和平均成績:
SELECT DISTINCT s.name,s.birthday,avg(sc.score) over(PARTITION by s.`name`) from score sc left JOIN student s on sc.sid = s.id
查詢mbatis 成績低于60的學生信息:
SELECT s.*,sc.course,sc.score FROM score sc LEFT JOIN student s on sc.sid = s.id where sc.course = 'mybatis' and sc.score < 60;
查詢學生成績前三名的記錄:
SELECT ROW_NUMBER() over() as '成績總分排名', sco.name,sco.allSco FROM ( SELECT DISTINCT s.`name` ,sum(sc.score) over(PARTITION by s.`name`) 'allSco' from score sc LEFT JOIN student s on sc.sid = s.id ORDER BY allSco desc LIMIT 3 ) as sco
查詢學生信息及年齡:
SELECT stu.name,stu.birthday,(YEAR(CURRENT_DATE) - YEAR(stu.birthday)) '年齡' from student stu
按平均成績從高到低顯示所有學生的所有課程的成績以及平均成績:
SELECT DISTINCT s.`name` ,sum(sc.score) over(PARTITION by s.`name`) 'allScore',avg(sc.score) over(PARTITION by s.name) '平均成績' from score sc LEFT JOIN student s on sc.sid = s.id ORDER BY allScore desc
查詢未成年的學生信息:
SELECT stu.name, stu.birthday, (year(CURRENT_DATE) - year(birthday)) 'age' from student stu where (year(CURRENT_DATE) - year(birthday)) < 18
查詢姓張的 學生信息:
SELECT * FROM student where name like '張%'
查詢本月過生日的學生信息:
SELECT * FROM student where MONTH(CURRENT_DATE) = MONTH(birthday)
查詢本周過生日的學生信息
SELECT * FROM student WHERE WEEKOFYEAR(CURRENT_DATE) = WEEKOFYEAR(birthday)
按各科成績進行排序,并顯示排名
SELECT stu.name , sc.course ,sc.score, RANK() over(PARTITION by sc.course ORDER BY sc.score desc) from score sc LEFT JOIN student stu on sc.sid = stu.id