If/Else statement return select query in T-SQL

Question

I need to write a store procedure for SQL Server. And it need to be something like:

Select * from tblSomething
Where param in (If param1 like 'string' select * from tblTable where condition1
            Else select * from tblTable where condition2)

The problem all the if else examples print something and don't return select query. Can you help???

Is it just me or does this question get more confusing due to the example posted? Provide sample data, expected results, etc. — JonH, May 31 '11 at 19:23

score 1 · Answer 1 · answered May 31 '11 at 19:24

1

IF param1 LIKE 'string'
    SELECT *
        FROM tblSomething
        WHERE param IN (SELECT * FROM tblTable WHERE condition1)
ELSE
    SELECT *
        FROM tblSomething
        WHERE param IN (SELECT * FROM tblTable WHERE condition2)

answered May 31 '11 at 19:24

Joe Stefanelli

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this works but you could also make this a boolean type expression using an OR. Ya it might be slower but its also smaller in size. +1 either way. – JonH May 31 '11 at 19:25

score 1 · Answer 2 · 2011-06-09T21:24:55.180

1

I'm not sure if that's what you're looking for.

IF EXISTS (SELECT * FROM tblSomething WHERE param1 like 'string')
  SELECT * FROM tblSomething WHERE param IN (SELECT * FROM tblTable WHERE condition1)
ELSE
  SELECT * FROM tblSomething WHERE param IN (SELECT * FROM tblTable WHERE condition2)

I'm new to TSQL so any comments to improve will be appreciated.

edited Jun 09 '11 at 21:24

answered May 31 '11 at 19:36

1

FYI about IF EXISTS (SELECT *...) ... http://stackoverflow.com/questions/3994040/sql-server-if-exists/3994059#3994059 or http://stackoverflow.com/questions/6137433/where-does-the-practice-exists-select-1-from-come-from/6137474#6137474 – gbn Jun 09 '11 at 21:03
Well I see; Thanks for the hint. I'll update it to `EXISTS (SELECT * ...`. And what about `TOP 1` in the query. Will `EXISTS (SELECT TOP 1 * FROM` be faster than `EXISTS (SELECT * FROM` ? – Jun 09 '11 at 21:22
2

Exactly the same. The TOP and select list are ignored (as per ANSI links) – gbn Jun 09 '11 at 21:23
1

I'm using this very often and I thought the `TOP 1 0` is faster but now I see it's even slower because it take some additional time to parse the `TOP 1` statement. Thanks man. – Jun 09 '11 at 21:28

If/Else statement return select query in T-SQL

2 Answers2