如何获得这个结果

Question

I have a dropdown on page when user selects any value from it ; i am passing that value and filtering the result. suppose if user select any bike from dropdown then from user table only those record should come which have that bike and also those records should come where user have not any bike .

   username               vehicleID 
   =========              =======
   john                   1
   peter                  1
   maria                  2
   raso                 
   pritam                 4

if user selects vehicleID 2 then raso should also come along with maria. I do not want to use UNION for this .

IF user does not select any thing all data should come by default on page

any other idea. thanks in advance

Answer 1

Use the following query, where the @VehicleID is the SelectedValue of the dropdownlist .

SELECT Username
FROM Table
WHERE @VehicleID IS NULL
OR VehicleID=@VehicleID
OR VehicleID IS NULL