title: Check if a parameter is null or empty in a stored procedure
body: <p>I know how to check if a parameter is null but i am not sure how to check if its empty ... I have these parameters and I want to check the previous parameters are empty or null and then set them like below</p>
  
  <pre><code>ALTER PROCEDURE [dbo].[GetSummary]
      @PreviousStartDate NVARCHAR(50) ,
      @PreviousEndDate NVARCHAR(50) ,
      @CurrentStartDate NVARCHAR(50) ,
      @CurrentEndDate NVARCHAR(50)
  AS
    BEGIN
      IF(@PreviousStartDate IS NULL OR EMPTY)
          SET @PreviousStartdate = '01/01/2010'  for example..
  </code></pre>
  
  <p>I would appreciate the help.</p>