Query with 2 variables

Question

I have a query with two variables (Employee and Date). The query is working fine if both of the variables are check and values assigned. But if only one variable is checked and a value assigned then the query will return 0 results. Is it possible that the query cannot work with only one variable out of the 2? Do I need a workaround or am i doing something wrong?
Here is the query:
SELECT T0.DocNum, T0.DocDate, T0.DocDueDate, T0.CardCode, T0.CardName, T0.Address, T0.DocTotal, T0.U_Employee, T1.firstName,T1.lastName,  T0.Comments FROM OVPM T0 LEFT JOIN OHEM T1 ON T0.U_EMPLOYEE = T1.FIRSTNAME' 'T1.LASTNAME WHERE T0.DocType = 'A' AND T0.U_EMPLOYEE = [%0] AND T0.DocDate =[%1].
Thank you so much for your help,
Irina Stanca

Answer 1

AFAIK, at least with 'complex queries' unchecked parameter gets
some default/blank value. Therefore, you should allow default values in your
WHERE clause.
You want: WHERE T0.COL = @VAR
You write: WHERE (T0.COL = @VAR OR [logical test for @VAR is a default value])
Snippets like this may help you in finding out that default value:
-- snip --
/SELECT FROM [dbo].[OHEM] T9/
declare @VAR_EMPL as char(20)
/* WHERE */
set @VAR_EMPL = /* T9.lastName */ '[%0]'
/SELECT FROM [dbo].[OVPM] T8/
declare @VAR_DATE as char(20)
/* WHERE */
set @VAR_DATE = /* T8.DocDate */ '[%1]'
SELECT '@VAR_EMPL: ' + '|' + @VAR_EMPL + '|' +  '@VAR_DATE: ' + @VAR_DATE + ' DATEDIFF: ' + cast(DATEDIFF(day, CAST('1900-01-01' as datetime), CAST(@VAR_DATE as datetime)) as varchar)
[/code]
-- snip --
Yes, it looks like the default value for dates is '1900-01-01'.
Therefore, you may want to code this way
.. WHERE (DocDate = @VAR_DATE OR DATEDIFF(day, CAST('1900-01-01' as datetime), CAST(@VAR_DATE as datetime)) > 0)
I also noticed a date-related issue that may cause problems in complex queries
if you work with dates from last century AND if your date format in B1 is YY instead of CCYY:
you enter 1907 and B1 interprets it as 2007.
HTH
Juha