Solved

How do I loop through each row in a table variable

Posted on 2009-04-14
8
1,046 Views
Last Modified: 2012-05-06
For MS SQL 2005. I have a table variable with no ID column. How do I loop through each row, or how do I create an ID column so I can loop through it?
0
Comment
Question by:NobleRLC
8 Comments
 
LVL 18

Expert Comment

by:UnifiedIS
ID: 24141659
What do you hope to accomplish by looping through the table?
0
 
LVL 39

Accepted Solution

by:
BrandonGalderisi earned 500 total points
ID: 24141684
I'm with unified in that you probably don't need to loop.  But here is how you define an ID column in your table variable.

declare @SomeTable table
  (ident       int identity primary key clustered
  ,field1       ......
....
)
0
 
LVL 22

Expert Comment

by:dportas
ID: 24141685
The simple answer is: Don't. It's better to avoid looping through rows one at a time by writing set-based queries instead. Also, every table should have a key. There's no excuse for not having one on a table variable.
0
Netscaler Common Configuration How To guides

If you use NetScaler you will want to see these guides. The NetScaler How To Guides show administrators how to get NetScaler up and configured by providing instructions for common scenarios and some not so common ones.

 

Author Comment

by:NobleRLC
ID: 24141832
I'm passing variables from the table variable to a stored procedure executed on each row.
0
 
LVL 22

Expert Comment

by:dportas
ID: 24142012
You could pass all the rows to the proc as a table-valued parameter.
Or you could write the proc so that it works on the whole result instead of one row at a time.

Try to avoid writing procs that need to be called for every single row. Doing it that way greatly increases the complexity of your code and destroys performance and scalability.
0
 
LVL 39

Expert Comment

by:BrandonGalderisi
ID: 24142134
Table valued parameters aren't available until 2008. :)  But the rest is all valid about doing procs to work with data sets not rows.
0
 
LVL 26

Expert Comment

by:Chris Luttrell
ID: 24142149
When you have to do something like that we avoid cursors and do something like the code below, assuming that you have to leave the original table alone and that your values are unique so the delete just deletes the one:

Select Variable 
into #TmpTable  -- could be table variable, but you have to set it up
from Table
 
DECLARE @thisVariable [typeneeded]
WHILE EXISTS (SELECT * FROM #tmpTable)
BEGIN
	SELECT TOP 1 @thisVariable = Variable FROM #TmpTable
	
	EXEC yourStoredProcedure (@thisVariable)
	
	DELETE FROM #TmpTable WHERE Variable = @thisVariable
END
DROP TABLE #TmpTable

Open in new window

0
 
LVL 22

Expert Comment

by:dportas
ID: 24142275
If you must call a proc for each row then I suggest you use an explicit DECLARE CURSOR iwith the FAST_FORWARD option. Using a cursor has the advantage over SELECT TOP because you can specify the order without having to requery the whole table on each iteration of the loop. Also a DECLARE CURSOR arguably makes it more explicit what is happening in loop.
0

Featured Post

Netscaler Common Configuration How To guides

If you use NetScaler you will want to see these guides. The NetScaler How To Guides show administrators how to get NetScaler up and configured by providing instructions for common scenarios and some not so common ones.

Question has a verified solution.

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

In this article we will get to know that how can we recover deleted data if it happens accidently. We really can recover deleted rows if we know the time when data is deleted by using the transaction log.
These days, all we hear about hacktivists took down so and so websites and retrieved thousands of user’s data. One of the techniques to get unauthorized access to database is by performing SQL injection. This article is quite lengthy which gives bas…
Video by: Steve
Using examples as well as descriptions, step through each of the common simple join types, explaining differences in syntax, differences in expected outputs and showing how the queries run along with the actual outputs based upon a simple set of dem…
Polish reports in Access so they look terrific. Take yourself to another level. Equations, Back Color, Alternate Back Color. Write easy VBA Code. Tighten space to use less pages. Launch report from a menu, considering criteria only when it is filled…

770 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