Comments on: SQL SERVER – INNER JOIN Returning More Records than Exists in Table

By: Nikki

Nikki — Fri, 01 Mar 2013 10:54:26 +0000

Thank you for your article. If you don’t mind, I have a question. I have two tables with information about a sales order. The left hand table contains one row of the sales order header information, sales order number and total etc. I need the required date for the order from the second table. The second table contains multiple rows per sales order as a customer may order an item with different delivery dates. However I only want to return the first required date from that table so that the query only ever outputs one row per sales order. How could I achieve this?

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Sat, 09 Feb 2013 01:31:38 +0000

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By: srikanth

srikanth — Wed, 30 Jan 2013 11:09:03 +0000

hi Pinal,

My name is srikanthreddy
How to use join more than three tables with in one query

By: Sahoo

Sahoo — Mon, 28 May 2012 14:16:56 +0000

Hi Pinal,

I have query related to joining. If I am using a OR condition to join 2tables then I am getting more than the expected number of records if the value matches with both conditions. For example.

select s.id, s.name1,s.name2,d.[desc]
from dbo.Test_Join_Source s
inner join dbo.Test_Join_Destination d
on
(s.name1=d.name1 or s.name2=d.name2)

The above query will produce 2 records if the source record matches by both the joining condition.
Question is, How do I prevent this.

By: Amir

Amir — Wed, 02 May 2012 13:08:06 +0000

We will come across Query3 type often (Ex : One to many Relationship)

By: Gurjit

Gurjit — Mon, 23 Apr 2012 20:07:20 +0000

Pinal Dave,

Sincere Thanks. Extremely good article.

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Sat, 18 Feb 2012 03:18:00 +0000

[...] SQL SERVER – INNER JOIN Returning More Records than Exists in Table [...]

By: Asha Bhatt

Asha Bhatt — Mon, 13 Feb 2012 10:06:08 +0000

Hi Pinal,

If Not Equal to Sign is giving the duplicate records then why we are using it. What is use of Not Equal to Sign in SQL?

Please tell me.

By: Ken

Ken — Sat, 11 Feb 2012 10:31:23 +0000

Note that “Null = Null is False” is the default behavior, not when you change that behavior with:
SET ANSI_NULLS OFF

Also “Null != Null is False” is always the same behavior, but the reason it is false changes because of the ANSI_NULLS setting.

By: Ken

Ken — Sat, 11 Feb 2012 10:17:13 +0000

I saw the challange and didn’t look at the article. Of course, it’s easy. When I did it, I used the “=” query instead of the != query which was my first choice, then, no, I want every table row picked in every join.:
DECLARE @tbl TABLE(i1 int)
INSERT INTO @tbl VALUES (1),(2),(3),(4),(5)
SELECT a.i1 first, b.i1 second
FROM @tbl a
INNER JOIN @tbl b
ON 1=1
Interesting that the result is the same as adding “ORDER BY b.i1, a.i1 so it processes from right to left. IE get the first record of the second table, find all the matches in the first table for that row… If I changed the insert order it would match that insert order since it is a heap table that hasn’t had a chance to fragment.

By: Ashlee Caul

Ashlee Caul — Fri, 10 Feb 2012 22:11:41 +0000

I can visualize what is happening here, but for those who cannot, try
SELECT f.Col1 fCol1, s.Col1 sCol1
so you can see the column that is matching. This may help you to understand why certain rows are returned.

By: SQL SERVER – A Quick Puzzle on JOIN and NULL – SQL Brain Teaser « SQL Server Journey with SQL Authority

Fri, 10 Feb 2012 01:31:33 +0000

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By: Ganesh narim

Ganesh narim — Thu, 09 Feb 2012 12:01:52 +0000

Hi pinal,

i send you one mail please do needful….!!!!!
Hope you help me….!!!

By: pinaldave

pinaldave — Thu, 09 Feb 2012 10:31:47 +0000

Excellent comment my friend. Love it!

By: Ganesh Narim

Ganesh Narim — Thu, 09 Feb 2012 09:40:35 +0000

Hi Pinal,

it is very nice example.

I like very much that Querry.1 it tells that.

Null = Null = False
Null is Null = True.

Wow..!! What a romantic SQL language we have..!!!!!
One of my friends asking me like this “How can i learn SQL Easily…!!!! is there any trick for this..???”

I told him that Do like this then you will get it easily..

Eat SQL,
Drink SQL,
Play With SQL,
Dream SQL,
Sing SQL,
Sleep with SQL,
Wake up with SQL……!!!!!

By: Sreelekha Vikram

Sreelekha Vikram — Thu, 09 Feb 2012 05:57:04 +0000

Hi Pinal,

Is this kind of behavior observed only in inner join or even in other joins?

By: Chirag Satasiya

Chirag Satasiya — Thu, 09 Feb 2012 05:18:02 +0000

Hi pinal sir,
We are also faced such kind of senarion many times while using inner join for more than 2 tables. We then find out that using proper join and distinct we are able to avoid such result.

Thank$
Chirag Satasiya

By: Dewesh Pushkar

Dewesh Pushkar — Thu, 09 Feb 2012 04:26:14 +0000

It was really awsome…….PINAL