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10774: alternatives to the OR sentence (dinamyc query)

Posted on 2014-11-20
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Last Modified: 2014-11-22
Hi experts:

I have a store procedure that can take 10 parameters. The user can enter 1,2,3 to 10 parameters. Do it OR is very expensive, can show T-SQL code to solve

SELECT
  *
  FROM TSQL2012.Production.Suppliers
  where city = @city OR phone = @phone OR contacttitle = @contacttitle OR country=@country
   ............. parametro10 = @parametro10
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Question by:enrique_aeo
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7 Comments
 
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Expert Comment

by:lcohan
ID: 40455779
Ever thought a UNION may work better? it implies DISTINCT so no duplicate rows will exists.
Or INTERSECT to get the row "identifier" in a CTE for instance than use that limited CTE record set to JOIN with actual table and get the rest of the columns
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Author Comment

by:enrique_aeo
ID: 40455788
Give me code T-SQL please
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Expert Comment

by:lcohan
ID: 40455814
SELECT * FROM TSQL2012.Production.Suppliers
WHERE city = @city
UNION
SELECT * FROM TSQL2012.Production.Suppliers
WHERE phone = @phone
UNION
SELECT * FROM TSQL2012.Production.Suppliers
WHERE contacttitle = @contacttitle
UNION
SELECT * FROM TSQL2012.Production.Suppliers
WHERE country= @country

And make sure you have an index on each of the above columns

And then you build your dynaminc SQL by not having in it the
...
UNION
SELECT * FROM TSQL2012.Production.Suppliers
WHERE country= @country
...

statement(s) where parameter value passed in IS NULL

and you execute the dynamic string by calling SP_EXECUTESQL
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Assisted Solution

by:lcohan
lcohan earned 600 total points
ID: 40455851
Or here - I think this is even better because it does not require dynamic SQL as the IS NOT NULL is included on each "branch" of the query. So all you need is pass NULL from app to the parameters you don't want/need in the SP and that particular select will return noting.



SELECT * FROM TSQL2012.Production.Suppliers
WHERE city = @city and @city IS NOT NULL
      UNION
SELECT * FROM TSQL2012.Production.Suppliers
WHERE phone = @phone and @phone IS NOT NULL
      UNION
SELECT * FROM TSQL2012.Production.Suppliers
WHERE contacttitle = @contacttitle  and @contacttitle IS NOT NULL
      UNION
SELECT * FROM TSQL2012.Production.Suppliers
WHERE country= @country and @country IS NOT NULL
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Assisted Solution

by:Scott Pletcher
Scott Pletcher earned 1400 total points
ID: 40456110
You really must use dynamic SQL to get good performance from these types of generic queries.  You can use sp_executesql, rather than EXEC, to drastically reduce the chance of SQL injection.
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Author Comment

by:enrique_aeo
ID: 40456265
ScottPletcher:

can you give me an example dynamic SQL
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Accepted Solution

by:
Scott Pletcher earned 1400 total points
ID: 40456280
Here's the simplest method, although you'll want to add checks to prevent SQL injection using this method:


DECLARE @sql varchar(max)
SET @sql = '
SELECT *
FROM TSQL2012.Production.Suppliers
WHERE 1 = 1'
IF @city > ''
    SET @sql = @sql + '
    AND (@city = city)'
IF @phone > ''
    SET @sql = @sql + '
    AND (@phone = phone)'
IF @contracttitle > ''
    SET @sql = @sql + '
    AND (@contacttitle = contacttitle)'
--IF ...other_parms...
    --SET ... + ...

EXEC (@sql)
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