String.IsNullOrEmpty like function for VARCHARs in SQL?

Question

Say I\'ve got a function or stored procedure that takes in several VARCHAR parameters. I\'ve gotten tired of writing SQL like this to test if these parameters have a value:

Answer 1

You can do ISNULL(@SomeVarcharParam, '') <> '' or you can create a UDF that returns a bit:

create function dbo.IsNullOrEmpty(@x varchar(max)) returns bit as
BEGIN
IF @SomeVarcharParm IS NOT NULL AND LEN(@SomeVarcharParm) > 0
    RETURN 0
ELSE
    RETURN 1
END

And call that using IF NOT dbo.IsNullOrEmpty(@SomeVarcharParam) BEGIN ...

Keep in mind that when calling a UDF, you MUST prefix the owner of it (here, dbo.)

Answer 2

Use this function (based on Derek's):

CREATE FUNCTION dbo.isNullOrEmpty(@x varchar(max)) RETURNS BIT AS
BEGIN
    IF @x IS NOT NULL AND LEN(@x) > 0
        RETURN 0

    RETURN 1
END

as

dbo.isNullOrEmpty(@someVar)

or

WHERE dbo.isNullOrEmpty(@someVar) = 1

in a stored procedure or query.

Answer 3

You can just do IF @SomeVarcharParam <> '' since the condition will evaluate to NULL and the branch won't be taken if the parameter is null

Answer 4

IF COALESCE(@SomeVarcharParm, '') <> ''
BEGIN
   -- do stuff
END