1、指定列：
select Sno,Sname from Student;
2、查询经过计算的值：
select Sname,’year of birth:’,2008-Sage,Sdept from student;
3、去除取值重复的行：
select distinct Sno from student;
4、满足条件的元组：
select Sname,Sage from Student
where Sdept =’CS’ AND Sage<=19;
5、确定范围，集合
select Sname from Student
where Sage BETWEEN 18 AND 20;
select Sname
from Student
where Sdept IN (‘CS’,'MA’);
6、匹配查询
select * from Student
where Sno LIKE ‘100%’;
7、Order By子句
select Sno,Grade from SC
where Cno =’2′
ORDER BY Grade DESC;
//DESC是降序，缺省为升序；
8、聚集函数：
select COUNT(Sno) from Student;
select AVG/MAX/MIN(Grade)
from SC
where Cno =’1′;
9、Group By子句：
Tags: mysql, sql, 数据库
select Cno,COUNT(Cno) from SC
GROUP BY Cno;
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