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

What you have there will return no row at all if the user doesn't exist. Here's what you need:

SELECT CASE WHEN EXISTS (
    SELECT *
    FROM [User]
    WHERE UserID = 20070022
)
THEN CAST(1 AS BIT)
ELSE CAST(0 AS BIT) END

Answer 2

Possibly something along these lines:

SELECT CAST(CASE WHEN COUNT(*) > 0 THEN 1 ELSE 0 END AS BIT)
FROM dummy WHERE id = 1;

http://sqlfiddle.com/#!3/5e555/1

Answer 3

Given that commonly 1 = true and 0 = false, all you need to do is count the number of rows, and cast to a boolean.

Hence, your posted code only needs a COUNT() function added:

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

Answer 4

select CAST(COUNT(*) AS BIT) FROM [User] WHERE (UserID = 20070022)

If count(*) = 0 returns false. If count(*) > 0 returns true.

Answer 5

Use 'Exists' which returns either 0 or 1.

The query will be like:

SELECT EXISTS(SELECT * FROM USER WHERE UserID = 20070022)

Answer 6

For those of you who are interested in getting the value adding a custom column name, this worked for me:

CAST(
    CASE WHEN EXISTS ( 
           SELECT * 
           FROM mytable 
           WHERE mytable.id = 1
    ) 
    THEN TRUE 
    ELSE FALSE 
    END AS bool) 
AS "nameOfMyColumn"

You can skip the double quotes from the column name in case you're not interested in keeping the case sensitivity of the name (in some clients).

I slightly tweaked @Chad's answer for this.