sql join return unwanted result

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i have two tables

Department
<img src="http://www9.0zz0.com/2015/02/14/00/463246826.png"/>

Instructor

<img src="http://www9.0zz0.com/2015/02/14/00/386938495.png"/>

i want to return department and it's manager

some departments have not managers so manager name should be null

but the result show cartisan product

result

SQL

select  dpt.Dept_Id , dpt.Dept_Name,dpt.Dept_Location, inst.Ins_Name as [Dept_Manager] ,dpt.Dept_Desc
 from  Department dpt  join Instructor as inst
     on (dpt.Dept_Id=3) AND ((dpt.Dept_Manager = inst.Ins_Id) OR (dpt.Dept_Manager is null))

<img src="http://www9.0zz0.com/2015/02/14/00/216699126.png"/>

result should be

Dept_Id Dept_Name Dept_Location Dept_Manager Dept_Desc
3 tes ma NULL NULL

so what is wrong with my code

Posted 13-Feb-15 10:12am

TheSniper105

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Comments

Zoltán Zörgő 13-Feb-15 16:19pm

- why are you referencing in two directios?
- you need LEFT JOIN

1 solution

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ZurdoDev · Accepted Answer · 2015-02-13T10:21:00

Solution 1

Just do a LEFT JOIN as mentioned in the comments.

SQL

SELECT *
FROM Department d
LEFT JOIN Instructor i ON d.dept_manager = i.ins_id
WHERE d.dept_id = 3

Posted 13-Feb-15 10:21am

ZurdoDev