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How to check if a table has at least one record in it ?

Posted on 2015-02-17
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Last Modified: 2015-02-21
I have a table, and I want to know if it has at least one record in it. If it the table does not have a record, then I want sql code execution to exit the stored procedure.
I came up with the following code, however I don't know if it is correct or not? I need help from an expert.

-- Code below is from stored procedure.
if not exists (select top 1 uid
               from user_detail
               where uid IS NOT NULL)
  retur
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Question by:brgdotnet
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6 Comments
 
LVL 37

Accepted Solution

by:
bbao earned 400 total points
ID: 40615860
it looks fine for me.

have you tried it using MS SQL?
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LVL 14

Assisted Solution

by:Mark Bullock
Mark Bullock earned 800 total points
ID: 40615867
EXISTS test for existence of rows.
The "top 1 uid" is not necessary because the sub-query can return any number of rows and result in a true value. You could use "uid" or "1" instead.
0
 
LVL 2

Author Comment

by:brgdotnet
ID: 40615871
When I run the query in Query Analyzer, it just comes back with an empty column. Anyway, I don't think my solution is the best approach. Perhaps someone can offer another solution. Plus how do I exit the stored procedure if the row does not exists? I put a return statement below, but I don't know if that is the correct syntax?

if not exists (select top 1 EmptyColumn
                from Table_3)
   return
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LVL 14

Assisted Solution

by:Mark Bullock
Mark Bullock earned 800 total points
ID: 40615883
Run the subquery, select top 1 EmptyColumn from Table_3. If you get records, the not exists statement will evaluate to false.

The return statement should work.
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LVL 52

Assisted Solution

by:Vitor Montalvão
Vitor Montalvão earned 400 total points
ID: 40616075
Your code it's OK. There is no better way to do it.
if not exists (select top 1 EmptyColumn 
                 from Table_3) 
    return 

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LVL 70

Assisted Solution

by:Scott Pletcher
Scott Pletcher earned 400 total points
ID: 40616843
I use a static 1 as the column, to avoid errors just in case the table definition changes, and the column you checked went away, although you directly reference a column anyway, so you could use "uid" instead of 1:

if not exists (select top (1) 1
        from dbo.user_detail
        where uid IS NOT NULL)
   return

Btw, you should add the parentheses around the "top" row count value, as that will be required in a future version of SQL.
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