SQL 唯一标识符到 varchar

Question

Im trying to achieve this in SQL Server:

exec proc_sample ''

but there is an error:

Error converting data type varchar to uniqueidentifier. Heres my sample proc:

CREATE PROCEDURE [dbo].[proc_sample]
( @ID uniqueidentifier )
AS BEGIN
IF
@ID IS NULL
OR @ID = ''
SELECT * FROM table1
ELSE
SELECT * FROM table2
END

I know that the issue is the OR @ID = '', but not sure how to fix it.

Answer 1

If you would like to pass a NULL parameter into the procedure then it should be assigned the default value NULL.

CREATE PROCEDURE [dbo].[proc_sample]
( @ID uniqueidentifier=NULL )
AS BEGIN
IF
@ID IS NULL
OR @ID = ''
SELECT * FROM table1
ELSE
SELECT * FROM table2
END

Answer 2

...just change the input @ID parameter to a character type

CREATE PROCEDURE [dbo].[proc_sample]
( @ID varchar(10))
AS BEGIN
IF
@ID IS NULL
OR @ID = ''
SELECT * FROM table1
ELSE
SELECT * FROM table2
END