t-sql looping through rows in a table

Posted on 2006-11-07
Last Modified: 2008-02-20
I have a need to loop through the rows of a temp table, compare certain columns, and perform an update on same columns.

I'm trying to accomplish this within a stored proc (sql server 2000).

Can someone provide sample code on how to do this or suggest a better way?

Note: I'm not to worried about efficiency at this point.

Question by:rutledgj
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LVL 28

Expert Comment

ID: 17889194
Use cursors
LVL 143

Expert Comment

by:Guy Hengel [angelIII / a3]
ID: 17889206
>Note: I'm not to worried about efficiency at this point.
note: you should ALWAYS worry about efficiency...

>I have a need to loop through the rows of a temp table, compare certain columns, and perform an update on same columns.
can you explain a bit in details?
usually, a simple UPDATE with CASE syntax can do the job.
LVL 28

Expert Comment

ID: 17889211
declare @col varchar(10),
 @co2 varchar(10)
declare c cursor for select column1, column2 from yourtable

open c
fetch next from c into into @co1 , @co2

while @@fetch_status = 0
if @co1= 1
update yourtable set @col=3 where @co2= @co2
fetch next from c into into @co1 , @co2
close c
deallocate c
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LVL 11

Expert Comment

ID: 17889226
Hi rutledgj,

do you realy need to loop through all the records this is very slow and totaly contary to set based processing

rather tell us your table structure and what you are tryong to update and we will try help you avoid cursors

> Note: I'm not to worried about efficiency at this point
but soon you will be :)



Expert Comment

ID: 17889249
Suppose you have all the conditions linked
Update #temp set col1 = val1, col2 = val2, col3 = val3
     where col1 in (select col1 from #temp where col1 = someval1) and
               col2 in (select col1 from #temp where col2 = someval2) and
               col2 in (select col1 from #temp where col3 = someval3)

If the columns you have are independant then break up the above query as
Update #temp set col1 = val1
     where col1 in (select col1 from #temp where col1 = someval)

and repeat it for the number of columns


Author Comment

ID: 17889484
My temp table is like this:

act_id, prop_id, act_date, prop_date, act_name, prop_name, etc

In the above table, act_id WILL always = prop_id but prop_date may not be the same as act_date. So I need to update the prop_date with the act_date.

LVL 143

Accepted Solution

Guy Hengel [angelIII / a3] earned 125 total points
ID: 17889504
this looks like you only needed this:

update yourtable
  set prod_date = act_date
where prod_date is null
  or prod_date <> act_date
LVL 28

Assisted Solution

imran_fast earned 125 total points
ID: 17889515
Update mytemptable set prop_Date = Act_date where act_id = prop_id

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