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  • SQL练习


    一、练习一

    sql:

    CREATE TABLE `Student` (
    	`SRUNO` INT ( 8 ) NOT NULL,
    	`SNAME` VARCHAR ( 12 ) NOT NULL,
    	`SEX` TINYINT ( 2 ) NULL,
    	`BIRTHDAY` VARCHAR ( 255 ) NULL,
    	`EMAIL` VARCHAR ( 255 ) NULL,
    	`SCORE` TINYINT ( 255 ) NULL,
    	`CLASSNO` TINYINT ( 0 ) NOT NULL DEFAULT Student AUTO_INCREMENT,
    	PRIMARY KEY ( `SRUNO` ) 
    );
    
    # 给表中一班的成绩加2
    UPDATE student SET score = score + 2 
    	
    # 给姓张的按成绩降序排序
    SELECT * FROM student WHERE SNAME LIKE '张%' ORDER BY score DESC;
    
    SELECT * FROM student WHERE SNAME LIKE '张%' ORDER BY score ASC;
    
    # 查询所有学生的生日
    select BIETHDAY from student;
    
    # 按班级编号统计各班的人数
    SELECT count(*) from student where classno = 1;
    SELECT count(*) from student where classno = 2;
    SELECT count(*) from student where classno = 3;
    
    # 最高分
    SELECT MAX(score) from student where classno = 1 ;
    #最低分
    SELECT MIN(score) from student where classno = 1 ;
    #平均分
    SELECT AVG(score) from student where classno = 1 ;

    # (5)
    SELECT classno,COUNT(classno),MAX(score),MIN(SCORE),AVG(SCORE) FROM student GROUP BY classno ORDER BY AVG(SCORE) DESC;

      

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  • 原文地址:https://www.cnblogs.com/aaaazzzz/p/12895327.html
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