Comments on: SQL SERVER – Solution Part 2 – A Quick Puzzle on JOIN and NULL – SQL Brain Teaser

By: SQL SERVER – Weekly Series – Memory Lane – #017 | SQL Server Journey with SQL Authority

Sat, 23 Feb 2013 01:31:27 +0000

[...] Solution Part 2 – A Quick Puzzle on JOIN and NULL – SQL Brain Teaser Some questions are timeless and they never grow old; no matter how much they grow old their interest never dies. Earlier, I asked a simple puzzle based on a conversation on SQLAuthority Page, and have received an overwhelming response from readers. I still get emails related to this puzzle every day. [...]

By: ChiragSatasiya

ChiragSatasiya — Tue, 21 Feb 2012 04:32:12 +0000

Hi Pinal Sir,
Thank you for selecting this as one of the answer for puzzle.

Thank$
Chirag Satasiya

By: sarita

sarita — Fri, 17 Feb 2012 18:31:07 +0000

How we can call a store procedure in crystal report

By: Khurram Amin

Khurram Amin — Fri, 17 Feb 2012 18:05:10 +0000

Hi Pinal
I initially wrong this but later today I run both queries and there is difference in execution plan as well, can you please explain two quries. Thanks,

SELECT st.col1
FROM FirstTable ft
Full OUTER JOIN SecondTable st ON st.Col1 = ft.Col1

Khurram

By: Ganesh narim

Ganesh narim — Fri, 17 Feb 2012 16:26:23 +0000

Hi pinal,

How are you doing..?

I feel happy to say that this “JOINS and NULL” issue came up with earlier blog comments you know that is your first reply to me i have commented on some posts before but i did not get any reply for that, i was happy when i found response for this post

http://blog.sqlauthority.com/2012/02/09/sql-server-inner-join-returning-more-records-than-exists-in-table/#comments

That time i was bit confusing when i was seaing the answer for query 1. suddenly i thought why jeff facing the duplicate problem with Joins even that join query1 not showing all including NULL’s,

i was serously thinking for some time i did some work later i realised with “NULL is NULL” and ‘not NULL=NULL’..

However in this post you are right i have thought it earlier in “SQL SERVER – Solution – A Quick Puzzle on JOIN and NULL – SQL Brain Teaser” but you mentioned clearly that not changing the T-SQL qury, if you ok with chaning the Query we have another solution for getting NULL valuse from both the tables.
(without using joins).

SELECT * FROM dbo.FirstTable
WHERE dbo.FirstTable.Col1 IS NULL

UNION ALL

SELECT * FROM dbo.SecondTable
WHERE dbo.SecondTable.Col1 IS NULL