SQL Server：将“ y”解释为BIT值

Question

In C, when you compared true/false value to 1/0, it worked very well.

I would want the similar possibility with SQL Server - when I have a bit column, I would like to compare myBitField = 'y' / myBitField = 'n'

Is there anything I can do about that? Maybe change some SQL interpreter settings or something?

Example of what I would like to do:

select * from
(
   select CAST(1 AS BIT) as result
) as main
where main.result = 'y'

Currently, it throws an error, and I would like it to return 1/true/'y', whatever, but I would like it to be able to make that comparison.

Answer 1

I suppose you want to do it for some yes/no thing. But this is generally a wrong concept, your application which is accessing the SQL Server should interpret y as a 1 and n as a 0 and afterwards set the correct parameters for the query. You should not (actually I'm temped to write "must not") do this in SQL Server, that's what you have a business logic for.

Answer 2

As others have said, BIT and CHAR / VARCHAR are entirely different datatypes. But if you want to cast them during the select, you can use CASE expression like so:

-- Reading string as BIT
SELECT CAST(CASE RESULT WHEN 'Y' THEN 1 WHEN 'N' THEN 0 ELSE NULL END AS BIT) RESULT

-- Reading BIT as string
SELECT CAST(CASE RESULT WHEN 1 THEN 'Y' WHEN 0 THEN 'N' ELSE NULL END AS CHAR(1)) RESULT

And that's about as far as your options go here, far as I can understand. :)