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原 入门oracle查询学生表语法

2019-01-18 03:00 381 查看

--单列排序(查询所有学生,按学号降序排序)
select * from tbl_student order by snum desc;
--多惗排序(查询所有学生,按照年龄升序排序,然后在按性别降序排列)
select * from tbl_student order by age,sex desc;
--查询学生年龄,要求不重复
select distinct age from tbl_student;
--统计不同年龄的数量
select count(distinct age) from tbl_student ;
--统计每个学生的总分,平均分,最高分,最低分
select snum,sum(score),avg (score),max(score),min(score)from tbl_grade group by snum;
--多分组字段类似于排序,先按第一个分组,在对已分好的组按第二个字段分组统计不同年龄,不同性别人数
select age,sex,count(*) from tbl_student group by age,sex;
--过滤掉最低分小于60的学生
select snum,sum(score)  ,avg(score),max(score) from Tbl_Grade
Group by snum having min(score)>=60;
--检索至少学过两门课的学生
select snum from tbl_grade group by snum having count(*)>=2;
--按照学生总分降序排序
Select snum,sum(score),avg(score),max(score),min(score)from tbl_grade
Group by snum order by sum(score)desc;
--查询有一门及格的学生
select * from tbl_student s
where 60<any(select score from tbl_grade g where s.snum=g.snum);
--或
select * from tbl_student s
where 60<some(select score from tbl_grade g where s.snum=g.snum);
--单行单列子查询
--查询学生的成绩,要求显示学生的姓名
select (select sname from tbl_student s where s.snum=g.snum) as sname,
       (select cname from tbl_course c where c.cnum=g.cnum) as cname,
       score from tbl_grade g;
 

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