Solved

What is the significance of a SELECT statement followed by the number 1 ?

Posted on 2007-04-03
2
202 Views
Last Modified: 2010-03-20
SELECT A.Branch, A.[E-Mail] INTO tblBrEmail From tblBranchEmails A WHERE EXISTS(SELECT 1 from tblFlLNExp  B, tblBranchNotRecd C WHERE Left(B.[CPS Account Number],3)=A.Branch AND Left(B.[CPS Account Number],3)=C.Branch) ORDER BY A.Branch"

What is the significance of the 1 in the (SELECT 1 ...) ?

Can this SQL statement be written without the 1 ?
0
Comment
Question by:zimmer9
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
2 Comments
 
LVL 35

Accepted Solution

by:
Raynard7 earned 350 total points
ID: 18847878
the row that is actually returned by the exists statement is irrelevant - exists looks to see if something is returned or not - most databases default to select 1 even if you specify a column - the 1 is faster to produce as it is a constant rather than row data.

so your query is saying where the sub query returns rows then show a.branch .... if it returns no rows then do not show that row from a
0
 
LVL 27

Assisted Solution

by:sujith80
sujith80 earned 150 total points
ID: 18856759
It needn't be "1". You can select any semantically correct value in the subquery used in EXISTS clause.
Say here, you can change "SELECT 1...." to any of the following, all means the same

SELECT 2 ....
SELECT 'x' ....
SELECT 'hello' ....
0

Featured Post

Free Tool: Subnet Calculator

The subnet calculator helps you design networks by taking an IP address and network mask and returning information such as network, broadcast address, and host range.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
T-sql Date Format 9 66
SQL Rewrite without the NULLIF 4 33
Create a Calendar table 29 43
how to use ROW_NUMBER() correctly 8 43
If you find yourself in this situation “I have used SELECT DISTINCT but I’m getting duplicates” then I'm sorry to say you are using the wrong SQL technique as it only does one thing which is: produces whole rows that are unique. If the results you a…
If you have heard of RFC822 date formats, they can be quite a challenge in SQL Server. RFC822 is an Internet standard format for email message headers, including all dates within those headers. The RFC822 protocols are available in detail at:   ht…
Finds all prime numbers in a range requested and places them in a public primes() array. I've demostrated a template size of 30 (2 * 3 * 5) but larger templates can be built such 210  (2 * 3 * 5 * 7) or 2310  (2 * 3 * 5 * 7 * 11). The larger templa…
Are you ready to implement Active Directory best practices without reading 300+ pages? You're in luck. In this webinar hosted by Skyport Systems, you gain insight into Microsoft's latest comprehensive guide, with tips on the best and easiest way…

734 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question