Return Boolean Value on SQL Select Statement

Question

How to return a boolean value on SQL Select Statement?

I tried this code:

SELECT CAST(1 AS BIT) AS Expr1
FROM [User]
WHERE (UserID = 20070022)


        

Answer 1

I do it like this:

SELECT 1 FROM [dbo].[User] WHERE UserID = 20070022

Seeing as a boolean can never be null (at least in .NET), it should default to false or you can set it to that yourself if it's defaulting true. However 1 = true, so null = false, and no extra syntax.

Note: I use Dapper as my micro orm, I'd imagine ADO should work the same.

Answer 2

Notice another equivalent problem: Creating an SQL query that returns (1) if the condition is satisfied and an empty result otherwise. Notice that a solution to this problem is more general and can easily be used with the above answers to achieve the question that you asked. Since this problem is more general, I am proving its solution in addition to the beautiful solutions presented above to your problem.

SELECT DISTINCT 1 AS Expr1
FROM [User]
WHERE (UserID = 20070022)

Answer 3

DECLARE @isAvailable      BIT = 0;

IF EXISTS(SELECT 1  FROM [User] WHERE (UserID = 20070022))
BEGIN
 SET @isAvailable = 1
END

initially isAvailable boolean value is set to 0