测试一下你的T-SQL基础知识-subquery

一直以为自己SQL挺好的,没有想到今天在重构存储过程遇到了一个子查询的问题,修改为自连接之后发现居然结果不对,于是有了下面的测试。假设表中有如下数数据,请问Query1,Query2,Query3的查询结果?

ID   OrderID TransID Type
1 1 1 E
2 1 1 A
3 1 1 B
4 1 2 A
5 1 2 B
6 2 1 A
7 2 1 B
8 2 2 A

 

--Query 1
SELECT * FROM OrderDetail a
left join OrderDetail b ON a.OrderID=b.OrderID and a.TransID=b.TransID and b.Goods='E'
WHERE b.Goods is  null

--Query 2
SELECT * FROM OrderDetail a
WHERE a.TransID <>
(
   SELECT top 1 b.TransID FROM OrderDetail b WHERE b.OrderID=a.OrderID and b.Goods='E'
)

--Query 3
SELECT * FROM OrderDetail a
WHERE NOT EXISTS 
(
    SELECT  b.TransID,b.orderid  FROM OrderDetail b WHERE b.OrderID=a.OrderID and b.Goods='E'
)

在查看运行结果前请默默的写下您的答案:
Query1

ID    OrderID    TransID    Goods
4    1    2    A
5    1    2    B
6    2    1    A
7    2    1    B
8    2    2    A
View Code

Query2

ID    OrderID    TransID    Goods
4    1    2    A
5    1    2    B
View Code

Query3

ID    OrderID    TransID    Goods
6    2    1    A
7    2    1    B
8    2    2    A
View Code

 

posted @ 2015-01-22 22:04  我是小马  阅读(434)  评论(0编辑  收藏  举报