mysql数据库练习

SELECT * FROM `student`

SELECT  count(*) as '人数' FROM student ;

SELECT  SUM(exam) as '总成绩' FROM schooldb where studentid='2011001003';

SELECT  avg(exam) as '平均分' FROM schooldb WHERE  studentid='2011001004';

SELECT max(exam) as '最大值',min(exam)as '最小值',avg(exam) as '平均值' FROM schooldb WHERE subjectid=2;

SELECT AVG(exam) as '平均分' FROM schooldb WHERE subjectid=1 and exam>60;

//....

SELECT sex,count(*) as '人数',addres FROM student GROUP BY sex,addres HAVING sex='男' and count(*)>2;

SELECT count(*) as '人数',gid FROM student GROUP BY gid HAVING count(*)>8;