Comments on: SQL SERVER – Common Table Expression (CTE) and Few Observation

By: Himadri

Himadri — Tue, 19 Mar 2013 07:58:11 +0000

Hello Pinal,

Which is faster as per performance (If I want to use in pagination)?
Identity column in temp table or ROW_NUMBER in CTE ?

By: Adam Misrahi

Adam Misrahi — Wed, 30 Jan 2013 16:48:17 +0000

A year and a half later but just in case it’s useful: I’m pretty certain a CTE could only improve performance as it amounts to little more than a way to alias a bit of code you’d like to repeat. In that sense the only effect it could have on the execution plan is making clear to the engine that it has to fetch something only once, not twice and that its self contained (no possibility of inline referencing a field outside its brackets).

By: Angad Singh

Angad Singh — Tue, 15 Jan 2013 10:23:52 +0000

Try this Amit,

create table #testme(
id int,
name char(2),
value int
)

insert into #testme
select 1,’a',100
union all
select 2,’b',200
union all
select 3,’c',300
union all
select 4,’d', 400

select t.id, t.name, t.value, SUM(t1.value) AS NewValue
from #testme t
inner join #testme t1 on t.id >= t1.id
group by t.id, t.name, t.value

By: Nisha

Nisha — Mon, 10 Dec 2012 07:56:30 +0000

Hi
Try This

CREATE TABLE #test
(
job varchar(100),
dept1 int,
dept2 int,
dept3 int
)

INSERT INTO #test VALUES(‘postman’, 100, 200, 300)

SELECT a.job,a.dept1,a.dept2,a.dept3,A1.[SUM]
FROM #test a
INNER JOIN
(
SELECT b.dept1+b.dept2+b.dept3 AS [SUM] ,b.job
FROM #test b
) A1 ON a.job = A1.job

By: Garry

Garry — Tue, 23 Oct 2012 23:01:52 +0000

just repeat the column again in select query

select MyTable.id,MyTable.name,MyTable.value,MyTable.value as newadd
from MyTable

By: sharath

sharath — Tue, 02 Oct 2012 07:03:03 +0000

hello sir,
my crytriea is like this

job dept1 dept2 dept3 sum

postman 100 200 300

how to do this

By: amit

amit — Mon, 01 Oct 2012 09:03:33 +0000

i have query
i need the result like
my table is
id name value
1 a 100
2 b 200
3 c 300

i need the result set like

id name value newadd
1 a 100 100
2 b 200 300
3 c 300 600

kindly let me know the query pls help me i am stuk in this

By: SQL SERVER – Convert Subquery to CTE – SQL in Sixty Seconds #001 – Video « SQL Server Journey with SQL Authority

Wed, 08 Feb 2012 01:32:10 +0000

[...] on CTE: Simple Example of Recursive CTE Multiple CTE in One SELECT Statement Query Common Table Expression (CTE) and Few Observation Delete Duplicate Rows Simple Example of Recursive CTE – Part 2 – MAXRECURSION – Prevent CTE [...]

By: SQL SERVER – Common Gotcha’s Associated with Common Table Expressions (CTE) – Quiz – Puzzle – 26 of 31 « SQL Server Journey with SQL Authority

Fri, 27 Jan 2012 01:31:14 +0000

[...] Server Interview Questions and Answers ISBN: 1466405643 Page#109-112 Common Table Expression (CTE) and Few Observation Multiple CTE in One SELECT Statement Query Delete Duplicate Rows Simple Example of Recursive CTE [...]

By: anil kumar gutlapalli

anil kumar gutlapalli — Tue, 31 May 2011 09:25:34 +0000

Pinal,

You are the most talented person in SQL i have ever seen!!!

Thank you for such a great geek info..!

By: Bob Pusateri

Bob Pusateri — Tue, 10 May 2011 16:33:08 +0000

Hi Pinal,

Thank you so much for contributing to T-SQL Tuesday and for sharing the links!

By: Ramdas

Ramdas — Tue, 10 May 2011 13:33:53 +0000

Nice discussion on CTE’s, I have Used CTE’s in certain scenarios and worked very well. I am just curious to know the Performance Hit on using CTE’s in more elaborate situations like trying to build a Bill Of Material for parts.

By: madhivanan

madhivanan — Tue, 10 May 2011 12:50:40 +0000

Becuase WITH is already a command used in options like backup with move, etc. So in order to differentiate, it should be preceded by a semicolon

By: madhivanan

madhivanan — Tue, 10 May 2011 12:49:14 +0000

1 Use temp table
2 Set based approach with single query

By: madhivanan

madhivanan — Tue, 10 May 2011 12:38:45 +0000

Please note that CTE can be used in a Single SELECT block only unlike temp table or table variable

By: Wilfred van Dijk

Wilfred van Dijk — Tue, 10 May 2011 09:47:19 +0000

I do not agree that CTE are not a replacement of temp table or Temp variable Table. I think it should be “CTE can be a replacement of temp table or temp variable table”.

I’ve seen and created many examples of T-SQL code where temptables are being replaced by CTE. In fact I recommend replacing a temptable by a CTE if possible.

By: Zafar

Zafar — Tue, 10 May 2011 06:40:36 +0000

How we can avoid cursors ?

By: Yap Chee Chau

Yap Chee Chau — Tue, 10 May 2011 05:25:13 +0000

Hi Pinal,

What is the main reason of always begin CTE with semi-comma ?