How can i store the result of a comparison into a variable

Question

I want to print a simple statement print (1=1), i expect the result to be TRUE or 1 but sql server tell me: Incorrect syntax near '='. why is that?

Same will happen for a statement like that

declare @test bit
set @test = (1=1)

in summary how can i "see" what is returned from a comparison without using an IF statement

Update: The reason i'm asking is because i'm trying to debug why the following statement

declare @AgingAmount smallint
set @AgingAmount = 500
select Amount, datediff(day,Batch.SubmitDate,getdate()) as Aging from myreporrt
where datediff(day,Batch.SubmitDate,getdate()) > @AgingAmount

will return all rows even with aging of 300 so i wanted to test if datediff(day,datesubmited,getdate()) > 500 returns true or false but could not find a way how to display the result of this comparison.

Answer 1

Although SQL Server has the concept of aboolean type, and it understands expressions that resolve to a boolean in IF and WHERE clauses, it does not support declaring boolean variables or parameters. The bit data type cannot store the result of a boolean expression directly, even though it looks suspiciously like one.

The nearest you can get to a boolean data type is this:

-- Store the result of a boolean test.
declare @result bit
select @result = case when <boolean expression> then 1 else 0 end

-- Make use of the above result somewhere else.
if @result = 1
    ...
else
    ...

To add to the confusion, SQL Server Management Studio treats bit like boolean when displaying results, and ADO.NET maps bit to System.Boolean when passing data back and forth.

Update: To answer your latest question, use the case when ... then 1 else 0 end syntax in the select statement.