Check if a parameter is null or empty in a stored procedure

Question

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 n

Answer 1

Here is the general pattern:

IF(@PreviousStartDate IS NULL OR @PreviousStartDate = '')

'' is an empty string in SQL Server.

Answer 2

I recommend checking for invalid dates too:

set @PreviousStartDate=case ISDATE(@PreviousStartDate) 
    when 1 then @PreviousStartDate 
        else '1/1/2010'
    end

Answer 3

You can try this:-

IF NULLIF(ISNULL(@PreviousStartDate,''),'') IS NULL
SET @PreviousStartdate = '01/01/2010'

Answer 4

To check if variable is null or empty use this

IF(@PreviousStartDate IS NULL OR @PreviousStartDate = '')

Answer 5

Another option:

IF ISNULL(@PreviousStartDate, '') = '' ...

see a function based on this expression at http://weblogs.sqlteam.com/mladenp/archive/2007/06/13/60231.aspx

Answer 6

If you want a "Null, empty or white space" check, you can avoid unnecessary string manipulation with LTRIM and RTRIM like this.

IF COALESCE(PATINDEX('%[^ ]%', @parameter), 0) > 0
    RAISERROR ...