尝试在参数中添加“ ALL”选项时，操作数类型冲突uniqueidentifier与int不兼容

Question

I created a drop down menu by getting values from the query. Now, I am trying to add "All" as the option instead of using multi select. I want the user either to select "All" or 1. Below is the query I am using and I run into this error message

operand type clash uniqueidentifier is incompatible with int

 select departmentid, name from department
 union
 select -1, 'ALL'

How can I add 'ALL' option and not run into this error?

Answer 1

How about using NULL instead?

select NULL, 'ALL'

Or generating an id on the fly?

select newid(), 'ALL'