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

I sometimes use NULLIF like so...

IF NULLIF(@PreviousStartDate, '') IS NULL

There's probably no reason it's better than the way suggested by @Oded and @bluefeet, just stylistic preference.

@danihp's method is really cool but my tired old brain wouldn't go to COALESCE when I'm thinking is null or empty :-)

Answer 2

To check if variable is null or empty use this:

IF LEN(ISNULL(@var, '')) = 0

Answer 3

I use coalesce:

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

Answer 4

What about combining coalesce and nullif?

SET @PreviousStartDate = coalesce(nullif(@PreviousStartDate, ''), '01/01/2010')

Answer 5

you can use:

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

Answer 6

If you want to use a parameter is Optional so use it.

CREATE PROCEDURE uspGetAddress @City nvarchar(30) = NULL, @AddressLine1 nvarchar(60) = NULL
    AS
    SELECT *
    FROM AdventureWorks.Person.Address
    WHERE City = ISNULL(@City,City)
    AND AddressLine1 LIKE '%' + ISNULL(@AddressLine1 ,AddressLine1) + '%'
    GO