想要避免笛卡尔积仍然得到2行而不是只有1行 [英] Want to avoid cartesian product still getting 2 rows instead of only ONE

问题描述

我正在研究Sql servar 2005;这是查询

I am working on Sql servar 2005; here is the query

SELECT distinct DailyAttendence.Empid,DailyAttendence.LeaveType,DailyAttendence.today as 'Half day taken at', EmployeeOnFulldayleave.LeaveDay FROM DailyAttendence
CROSS JOIN EmployeeMaster CROSS JOIN EmployeeOnFulldayleave
where DailyAttendence.LeaveType='h' and EmployeeOnFulldayleave.fleave =1 and DailyAttendence.Empid=2

它仍然显示两条记录！它应该只有一个记录！



2 H 06-08-2013 06-08-2013

it is still showing two records! it should only be one record!

2 H 06-08-2013 06-08-2013

2 H 06-08-2013 06-09-2013



PLZ帮我吧！

感谢提前

Priya Tiwari

2 H 06-08-2013 06-09-2013

plz help me its urgent!
Thankx in advance
Priya Tiwari

推荐答案

它们是截然不同的 - 所以它正在做它应该做的事情。您的查询返回两条符合条件的记录 - 因此您需要优化条件，或者使用TOP限制返回的记录数：

They are distinct and different - so it is doing exactly what it should. Your query returns two records which match your criteria - so either you need to refine your criteria, or limit the number of record you return with TOP:

SELECT DISTINCT TOP 1 ...

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