Question

I have a table name Students having (studentId, StudentName,Address,PhoneNo)

i have provided a filter for user to select only StudentId from Combobox to get the details of Students… and generate Report.

I have written following Query to get student Detail :

(select * from Students where StudentId = stdId)

Here stdId is a Parameter that i pass from code

It works fine if i select single studentId…. But in user selection Comobobox i have also provided "ALL" if user Select All from combobox i want to display details of all student

So what should I pass in stdId if user selects All ?

I used inline Query in C# (not using SQL Stored Procedure)

Answer 1

You can do it like this .

SELECT * from Students s
WHERE s.studentId = ISNULL(@StudentId,s.studentId) 

When “All” is selected in combo box pass null in your @studentid parameter. If you can not pass null in parameter then pass -1 or anything which can not be contain in you combox option and do it like this:(if -1= All)

 SELECT * from Students s
 WHERE s.studentId = @StudentId or @StudentId=-1

You can also try the answer given by Curt.