Dynamic WHERE CLAUSE IN SQSERVER 2008 EXP.

=== @population nvarchar(max)

declare    @chvSelect varchar(max),
             @chvFrom varchar(max),
             @chvWhere varchar(max),
             @chvOrderby varchar(max),
             @chvSQL varchar(max)
BEGIN
 

--if @Population is not null

set @chvSelect='SELECT Localities.Name,FormFields.FieldName, FormInstanceData.Value'  
set @chvFrom=' FROM   FormInstances INNER JOIN
                      FormInstanceData ON FormInstances.Id = FormInstanceData.FormInstanceId INNER JOIN
                      Communities INNER JOIN
                      Localities ON Communities.Id = Localities.Id INNER JOIN
                      WCData ON Localities.Id = WCData.LocalityId ON FormInstances.Id = WCData.FormInstanceId INNER JOIN
                      FormFields ON FormInstanceData.FieldId = FormFields.Id '
set @chvWhere=' WHERE FormFields.FieldName =' + @Population 
--if @Population is not null

--set @chvWhere=@chvWhere + 'FormFields.FieldName =' + CONVERT(varchar,@Population )
set @chvSQL = @chvSelect+ @chvFrom + @chvWhere 
select @chvSQL Query
  --if @debug = 0
        exec (@chvSQL)
  --   else
   --    select @chvSQL

END