标签：sql
针对一个表练习
create table student(name Char(20),curriculum Char(20),score Char(20));
INSERT INTO student (name,curriculum,score) VALUES(‘王五‘,‘数学‘,‘100‘);
mysql> select * from student;
+--------+------------+-------+
| name | curriculum | score |
+--------+------------+-------+
| 张三 | 语文 | 81 |
| 张三 | 数学 | 75 |
| 李四 | 语文 | 76 |
| 李四 | 数学 | 90 |
| 王五 | 语文 | 81 |
| 王五 | 数学 | 100 |
+--------+------------+-------+
select distinct name from student where name not in (select distinct name from student where score<80);
+--------+
| name |
+--------+
| 王五 |
+--------+
select distinct * from student where name not in (select distinct name from student where score<80);
+--------+------------+-------+
| name | curriculum | score |
+--------+------------+-------+
| 王五 | 语文 | 81 |
| 王五 | 数学 | 100 |
+--------+------------+-------+
select distinct * from student where name not in (select distinct name from student where score<80) group by name;
+--------+------------+-------+
| name | curriculum | score |
+--------+------------+-------+
| 王五 | 语文 | 81 |
+--------+------------+-------+
(2)形成如下表格
+--------+--------+--------+
| name | 语文 | 数学 |
+--------+--------+--------+
| 张三 | 81 | 75 |
| 李四 | 76 | 90 |
| 王五 | 81 | 100 |
+--------+--------+--------+
答案：
select name,(select score from student s where curriculum=‘语文‘ and s.name=student.name) as 语文, (select score from student s where curriculum=‘数学‘ and s.name=student.name) as 数学 from student group by name;
+--------+------------+-------+-----------+
| name | curriculum | score | pass |
+--------+------------+-------+-----------+
| 张三 | 语文 | 81 | 及格 |
| 张三 | 数学 | 75 | 不及格 |
| 李四 | 语文 | 76 | 不及格 |
| 李四 | 数学 | 90 | 及格 |
| 王五 | 语文 | 81 | 及格 |
| 王五 | 数学 | 100 | 及格 |
+--------+------------+-------+-----------+
select name, curriculum,score,(CASE WHEN student.score>=80 THEN ‘及格‘ ELSE ‘不及格‘ END) as pass from student ;
+--------+------------+-------+
| name | curriculum | score |
+--------+------------+-------+
| 王五 | 数学 | 100 |
| 李四 | 数学 | 90 |
| 张三 | 语文 | 81 |
| 王五 | 语文 | 81 |
| 李四 | 语文 | 76 |
| 张三 | 数学 | 75 |
+--------+------------+-------+
答案：（+0因为是char转int）
select * from student order by score+0 desc ;/********************************
* 本文来自博客 “李博Garvin“
* 转载请标明出处:http://blog.csdn.net/buptgshengod
******************************************/
标签：sql
原文地址：http://blog.csdn.net/buptgshengod/article/details/45025889
