Stored Procedure Where Clause Parameters

Question

I've got an ASP.net search page where the user can enter one or more search criteria. The page calls a stored procedure to query a MS SQL Server 2008 db.

Part of the search criteria is single date or date range. If the user supplies Date1, we search on a single date. If the user supplies Date1 and Date2, we search on a date range.

My issue is coding this logic in the stored proc.

@Date1 datetime
@Date2 datetime
..other search params...

So there are three conditions:

1. Both @Date1 and @Date2 are null (the user is not searching on dates)
2. @Date1 is not null and @Date2 is null (the user is searching on a single date)
3. @Date1 is not null and @Date2 is not null (user is searching a date range)

I can't figure out how to structure the WHERE clause to handle each of the three possible conditions.

I'm familiar with ISNULL() and COALESCE()

Any tips or suggestions are greatly appreciated.

Answer 1

CREATE PROCEDURE BLABLABLA(
  @DATE1 DATETIME = NULL,
  @DATE2 DATETIME = NULL
)
AS
BEGIN
  SELECT COL1, COL2
  FROM THE_TABLE
  WHERE 
    THE_TABLE.DATETIMEFIELD BETWEEN 
      ISNULL(@DATE1, THE_TABLE.DATETIMEFIELD) 
      AND COALESCE(@DATE2, @DATE1, THE_TABLE.DATETIMEFIELD)
END

Another choice, losing some expressiveness but likely using indexes, could be:

CREATE PROCEDURE BLABLABLA(
  @DATE1 DATETIME = NULL,
  @DATE2 DATETIME = NULL
)
AS
BEGIN
  SELECT COL1, COL2
  FROM THE_TABLE
  WHERE 
    (THE_TABLE.DATETIMEFIELD >= @DATE1 OR @DATE1 IS NULL) 
     AND (THE_TABLE.DATETIMEFIELD <= @DATE2 
         OR THE_TABLE.DATETIMEFIELD = @DATE1
         OR (@DATE1 IS NULL AND @DATE2 IS NULL)) 
END

Answer 2

You could try to create your SQL query as a string in the SP and then execute it, like this:

...
declare @sql varchar(500)
set @sql = 'select from myTable where 1=1'

if(@Date1 <> null)
    set @sql = @sql + ' and date1 >= '+ @date1

if(@Date2 <> null)
    set @sql = @sql + ' and date2 <= '+ @date2

print(@sql) -- for debug 
exec(@sql)