SQL Joining three tables and using LEFT OUTER JOIN

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SQL Joining three tables and using LEFT OUTER JOIN

Author

Topic

dejan88
Starting Member

7 Posts

Posted - 2012-03-19 : 05:30:08

I have three tables and two seperate SQL queries which are working correctly and I am having correct results. If I try to join these three tables I am having null as result.

First query:

select T1.ID,T3.COMPANY
from T1,T3
where (T1.status!='CLOSED') and (T1.PRIORITY)>5 and T1.CLASSID=T3.CLASSID

Second query:

SELECT T1.ID, T2.DESCRIPTION
FROM T1
LEFT OUTER JOIN T2
ON T1.ID=T2.KEY
WHERE T1.status!='CLOSED'
AND (T2.CREATEDATE= (SELECT MAX(CREATEDATE)
FROM T2
WHERE T2.KEY=T1.ID))

I tried to join them but as result I am having null:

select T1.ID,T3.COMPANY,T2.DESCRIPTION
from T1
INNER JOIN T3 ON T1.CLASSID=T3.CLASSID
LEFT OUTER JOIN T2
ON T1.ID=T2.KEY
where (T1.status!='CLOSED') AND (T1.PRIORITY)>5
AND (T2.CREATEDATE= (SELECT MAX(CREATEDATE)
FROM T2
WHERE T2.KEY=T1.ID))

What am I doing wrong? Thanks for help

RickD
Slow But Sure Yak Herding Master

3608 Posts

Posted - 2012-03-19 : 07:05:04

You are turning your l;eft join into an inner join in your Where clause, try this instead:


select T1.ID,T3.COMPANY,T2.DESCRIPTION 
from T1
INNER JOIN T3 
ON T1.CLASSID=T3.CLASSID
AND (T1.status!='CLOSED') 
AND (T1.PRIORITY)>5
LEFT OUTER JOIN T2
ON T1.ID=T2.KEY 
AND (T2.CREATEDATE= (SELECT MAX(CREATEDATE) 
						FROM T2
						WHERE T2.KEY=T1.ID)
)

visakh16
Very Important crosS Applying yaK Herder

52326 Posts

Posted - 2012-03-19 : 08:58:56

see

http://weblogs.sqlteam.com/jeffs/archive/2007/05/14/criteria-on-outer-joined-tables.aspx

------------------------------------------------------------------------------------------------------
SQL Server MVP
http://visakhm.blogspot.com/

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