Comments on: SQL SERVER – 2005 Explanation Left Semi Join Showplan Operator and Other Operator

By: Mycroft

Mycroft — Fri, 17 Jun 2011 03:35:57 +0000

If a Left Anti Semi join is taking 75% of the query cost is there any way to mitigate that cost.

You’re explanation seems to just be the MSDN info represented with an example!

By: Shantanu

Shantanu — Sun, 05 Jun 2011 16:22:46 +0000

I am not clear with any of these. Please put some light on it what exactly it do.

“If no join predicate exists in the Argument column, each row is a matching row.”

By: Gabe

Gabe — Tue, 03 Nov 2009 21:00:40 +0000

I know this is a year ago, but for anyone who’s having this issue like Frank, you can easily use a full outer join to accomplish this goal.

Assume that the column a is the cat_id.

declare @cat table(a int, b int)

declare @person table(a int, b int)

insert into @cat
select 1,1
union
select 2,2

insert into @person
select 1,1
union
select 3,3

select *
from @cat m
full outer join @person m2
on m.a = m2.a

By: Frank

Frank — Fri, 16 May 2008 23:39:51 +0000

I cannot figure out how to do the following, and it is really irking me:

I have, say, 6 tables, I want to include all of the records associated with the first table’s ID value, somewhere down the line in the joins, however, I want to get any values that exist between two child tables and still return results if neither of them exist.

Like:

select * from house left join person on house.houseid=person.houseid –Now here is the tricky part
some join cat on person.catID=cat.catID

I want to return all houses. I want to return all persons. Left and full joins will not return the records if neither a person or a cat exists…

What can I do with this?

Thanks for your help.

Frank