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using variables in whereclause

Posted on 2012-03-29
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Last Modified: 2012-03-29
Hi,
  I have something like below in my stored procedure

IF @physicianID = 0 OR @physicianID IS NULL
BEGIN
SET @whereClause = 'requestedby=@physicianID
            and examdate>=@startDate
            and examdate<=@endDate'
END
ELSE
BEGIN
SET @whereClause ='examdate>=@startDate
            and examdate<=@endDate'
END

and I used the variable @whereCluase like below

select
            examdate,
            patient_no
      from exams
      where @whereClause
      group by examdate,patient_no
Can I do like this? or please let me know how can I do that .

Thank you
0
Comment
Question by:Sthokala
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7 Comments
 
LVL 59

Expert Comment

by:HainKurt
ID: 37783272
after your code do his

declare @sql varchar(max) = 'select ... from ...' + @whereClause
exec @sql
0
 
LVL 59

Expert Comment

by:HainKurt
ID: 37783288
oops, you need to work on this part too

SET @whereClause = 'requestedby=@physicianID
            and examdate>=@startDate
            and examdate<=@endDate'
>>>>
SET @whereClause = 'requestedby=' + @physicianID +
          ' and examdate>= ''' + @startDate + ''''
          ' and examdate<= ''' + @endDate + ''''
0
 
LVL 59

Expert Comment

by:HainKurt
ID: 37783311
and I guess there is logical error in your code "if... then ... else..." logic should be reversed...

so, final structure should be something like this

declare @whereClause varchar(max)
declare @startDate varchar(12)
declare @endDate varchar(12)
declare @physicianID int

IF isNull(@physicianID,0) = 0
BEGIN 
  SET @whereClause ='examdate >= ''' + @startDate + ''' and examdate <= ''' + @endDate + ''''
END
ELSE
BEGIN
  SET @whereClause = 'requestedby=' + @physicianID + ' and examdate>= ''' + @startDate + ''' and examdate<= ''' + @endDate + ''''
END

declare @sql varchar(max) = 'select ... from ...' + @whereClause
exec @sql

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LVL 70

Expert Comment

by:Scott Pletcher
ID: 37783340
You have two choices:
    1.  Use one query, which tests the variable and column as needed.  
         This may not produce an optimal query plan every time it run.
    2.  Use dynamic SQL, which will produce an optimal query plan, but is more work
         to set up **and requires specific authorities being granted *directly* to the id
         used to run the SQL code**.


--1.
SELECT
            examdate,
            patient_no
      FROM dbo.exams
      WHERE
          (@physicianID = 0 OR @physicianID IS NULL OR requestedby = @physicianID) AND
          examdate>=@startDate and
          examdate<=@endDate'
      GROUP BY
          examdate, patient_no
0
 
LVL 70

Accepted Solution

by:
Scott Pletcher earned 2000 total points
ID: 37783367
--2.

DECLARE @sql nvarchar(max)

SET @sql = '
SELECT
            examdate,
            patient_no
      FROM dbo.exams
      WHERE
          examdate>=@startDate AND
          examdate<=@endDate
'

IF @physicianID > 0
    SET @sql = @sql + ' AND
           requestedby = ' + CAST(physicianID AS varchar(10))

SET @sql = @sql + '
       GROUP BY
          examdate, patient_no'

EXEC sp_executesql @sql, N'@startDate datetime, @endDate datetime', @startDate, @endDate
0
 

Author Comment

by:Sthokala
ID: 37783530
Hi,
  Thank you for your comments.  I tried below way

DECLARE @sql nvarchar(max)

SET @sql = ' INSERT INTO #TmpMUStatus
   SELECT count(*), (SELECT name from users where user_no='+CAST(@physicianID AS varchar(10))+') as physicianName,null,null,null,null,null,null,null,null,null,null,NULL,NULL from(
      SELECT
            examdate,
            patient_no
      FROM exams WHERE
          examdate>='+LEFT(CONVERT(VARCHAR, @startDate, 120), 10)
+' AND
          examdate<='+LEFT(CONVERT(VARCHAR, @endDate, 120), 10)

IF @physicianID > 0
    SET @sql = @sql + ' AND
           requestedby = ' + CAST(@physicianID AS varchar(10))

SET @sql = @sql + '
        GROUP BY examdate,patient_no) AS SourceQuery'
EXEC @sql


I am getting below error

Msg 203, Level 16, State 2, Procedure GenerateMUStats, Line 54
The name ' INSERT INTO #TmpMUStatus
   SELECT count(*), (SELECT name from users where user_no=73408) as physicianName,null,null,null,null,null,null,null,null,null,null,NULL,NULL from(
      SELECT
            examdate,
            patient_no
      FROM exams WHERE
          examdate>=2012-01-01 AND
          examdate<=2012-05-05 AND
           requestedby = 73408
        GROUP BY examdate,patient_no) AS SourceQuery' is not a valid identifier.
0
 
LVL 70

Expert Comment

by:Scott Pletcher
ID: 37783579
EXEC (@sql) -- the parens are required


Since you want pass to the date values in, you also need additional quotes:

...
FROM exams WHERE
          examdate>='''+LEFT(CONVERT(VARCHAR, @startDate, 112), 8)
+''' AND
          examdate<='''+LEFT(CONVERT(VARCHAR, @endDate, 112), 8) + ''''
...
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