Solved

SQL - Column doesn't exists error

Posted on 2013-05-30
5
549 Views
Last Modified: 2013-06-03
Hello experts,

I have 2 databases for the same system, but since it's different versions one has additional columns and the other one doesn't.  I'm using the same query to pull from both databases.

I am getting an error if I use the query with the extra column to pull from the database that doesn't have it.  How could I set it to null if it doesn't have the extra column?

SELECT ID, NAME, DEF_ID FROM VENDOR

The column "DEF_ID" is a new field in the current database.  It is returning an error.
0
Comment
Question by:holemania
[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
  • 3
  • 2
5 Comments
 
LVL 41

Expert Comment

by:ralmada
ID: 39207896
try

if col_length('vendor, 'DEF_ID') is null
      SELECT ID, NAME, DEF_ID FROM VENDOR
else
      SELECT ID, NAME, null as def_id FROM VENDOR
0
 
LVL 69

Accepted Solution

by:
Scott Pletcher earned 400 total points
ID: 39208358
Even without the minor syntax problem, the above code won't work.

Assuming permissions aren't an issue, you can use dynamic SQL:

DECLARE @sql varchar(8000)

SET @sql = 'SELECT ID, NAME'
IF COL_LENGTH('vendor', 'DEF_ID') > 0
    SET @sql = @sql + ', DEF_ID'
SET @sql = @sql + ' FROM DBO.VENDOR'
EXEC(@sql)
0
 
LVL 41

Assisted Solution

by:ralmada
ralmada earned 100 total points
ID: 39208480
I guess you're referring to this syntax issue:

if col_length('vendor, 'DEF_ID') >0
      SELECT ID, NAME, DEF_ID FROM VENDOR
else
      SELECT ID, NAME, null as def_id FROM VENDOR

I too was considering going dynamic but I think this is what the asker is looking for:

set @sql = 	'select id, name,' + 
		case when col_length('vendor', 'def_id') > 0 then 'def_id' else 'null as def_id' end + 
		' from vendor'
exec(@sql)

Open in new window

0
 
LVL 69

Expert Comment

by:Scott Pletcher
ID: 39209163
The missing quote after vendor is the syntax issue.

The code you wrote won't work on a database where the vendor table doesn't contain a "DEF_ID" column, because SQL can't generate a plan for that query -- you have to remember that SQL has to pre-generate a plan for the query before the code runs and thus before the IF gets evaluated at run time.  Try the code and you'll see what I mean.
0
 
LVL 41

Expert Comment

by:ralmada
ID: 39209190
Correct, the IF won't work, but the dynamic SQL alternative with the null in case the column doesn't exists will (http:#a39208480). And I think that's what the asker is looking for.
0

Featured Post

What is SQL Server and how does it work?

The purpose of this paper is to provide you background on SQL Server. It’s your self-study guide for learning fundamentals. It includes both the history of SQL and its technical basics. Concepts and definitions will form the solid foundation of your future DBA expertise.

Question has a verified solution.

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

Suggested Solutions

Introduction: When running hybrid database environments, you often need to query some data from a remote db of any type, while being connected to your MS SQL Server database. Problems start when you try to combine that with some "user input" pass…
This article describes how to use the timestamp of existing data in a database to allow Tableau to calculate the prior work day instead of relying on case statements or if statements to calculate the days of the week.
The Email Laundry PDF encryption service allows companies to send confidential encrypted  emails to anybody. The PDF document can also contain attachments that are embedded in the encrypted PDF. The password is randomly generated by The Email Laundr…
Finding and deleting duplicate (picture) files can be a time consuming task. My wife and I, our three kids and their families all share one dilemma: Managing our pictures. Between desktops, laptops, phones, tablets, and cameras; over the last decade…

732 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