conditional stored procedure with/without passing parameter

Question

I created a stored procedure which when passed nothing as parameter should return the entire table. But if the studentId is passed, then return her details. Something like t

Answer 1

Shorter way to do that:

create procedure usp_GetStudents @studentId int = null
as
  select * from Student 
  where studentId = isnull(@studentId,studentId)

You can't chack if value is null using =. For your example you have to replace condition @studentId = null to is null syntax.

Try to change your code as below:

create procedure usp_GetStudents @studentId int = null
as
  if (@studentId is null)
    select * from Student
  else
    select * from Student where studentId = @studentId