Why do I receive a Mutator error when modifying an Xml value in Sql

Question

I have the following stored procedure:

ALTER PROCEDURE [dbo].[UpPro]
(
    @PN varchar(200),
    @xml xml,
    @gVa varchar(10),
)
AS
/* update the gender */         


        

Answer 1

The error actually says it all, @XML is null and that is not allowed.

Repro:

declare @X xml;

set @X.modify('replace value of text()[1] with "1"');

Msg 5302, Level 16, State 1, Line 4 Mutator 'modify()' on '@X' cannot be called on a null value.

Check for null before you modfy.

declare @X xml;

if @X is not null
  set @X.modify('replace value of text()[1] with "1"');