Conditional Query

[Jeff Mason]

Hi,

I'm trying to construct a query (in a stored procedure) which will have a number of
selection criteria based on input parameters. There are a number of these parameters
whose selection conditions they represent which all have to be true for a row to be
returned in the resultset.

The basic query is:

SELECT Store, StoreNumber
FROM Stores
WHERE ...

I'm trying to come up with the WHERE clause.

For example, I want to define a parameter named @ExcludeSpecialties which if it has
the value 1, means to return all stores but exclude stores whose StoreNumber is in
the list (800, 802, 804). If the parameter has the value 0, then it means "don't
care" and all StoreNumbers should be returned.

One could certainly argue that there probably should have been an column in the
Stores row to indicate the store is a specialty store, rather than using a hard-wired
list of numbers. But the current data schema cannot be easily changed. Besides, the
list never changes.

Indeed, there is a Franchise bit column in the row which is selected by another
parameter called @ExcludeFranchise whose WHERE predicate could be written as:

WHERE Franchise = CASE WHEN @ExcludeFranchise = 1 THEN 0 ELSE Franchise END

and if all the parameters were like this, I wouldn't be posting. Sadly, for the
Specialties test I'm stuck with a NOT IN list.

This is easy enough to do in an IF/ELSE block, but there are several such similar
parameters whose values may be specified in any combination. This, I think, makes
IF/ELSE impractical as the number of IF/ELSE statements to handle all possible
combinations would grow very quickly.

I'm hoping there is a simple solution to this NOT IN list, and it's just that I can't
see it.

Can anyone help?

Thanks,

-- Jeff

[Erland Sommarskog]

Jeff Mason (je******@comcast.net) writes:

I'm trying to construct a query (in a stored procedure) which will have
a number of selection criteria based on input parameters. There are a
number of these parameters whose selection conditions they represent
which all have to be true for a row to be returned in the resultset.

I have an article on by web site that discusses a couple of alternatives,
both with static and dynamic SQL:
http://www.sommarskog.se/dyn-search.html

--
Erland Sommarskog, SQL Server MVP, es****@sommarskog.se

Books Online for SQL Server 2005 at
http://www.microsoft.com/technet/pro...ads/books.mspx
Books Online for SQL Server 2000 at
http://www.microsoft.com/sql/prodinf...ons/books.mspx

[Hugo Kornelis]

On Thu, 27 Apr 2006 11:10:01 -0400, Jeff Mason wrote:

(snip)

For example, I want to define a parameter named @ExcludeSpecialties which if it has
the value 1, means to return all stores but exclude stores whose StoreNumber is in
the list (800, 802, 804). If the parameter has the value 0, then it means "don't
care" and all StoreNumbers should be returned.
Hi Jeff,

WHERE ( @ExcludeSpecialties = 0 OR StoreNumber NOT IN (800, 802, 804) )

(snip)Indeed, there is a Franchise bit column in the row which is selected by another
parameter called @ExcludeFranchise whose WHERE predicate could be written as:

WHERE Franchise = CASE WHEN @ExcludeFranchise = 1 THEN 0 ELSE Franchise END

and if all the parameters were like this, I wouldn't be posting. Sadly, for the
Specialties test I'm stuck with a NOT IN list.

That is indeed a common method to write such queries.

Do read the article Erland posted a link to - it describes a bunch of
methods to achieve what you need, with all their strengths and
weaknesses. Good stuff!

--
Hugo Kornelis, SQL Server MVP