在SQL Select语句上返回布尔值 [英] Return Boolean Value on SQL Select Statement

问题描述

如何在SQL Select语句上返回布尔值?

How to return a boolean value on SQL Select Statement?

我尝试了以下代码:

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

并且仅当表上存在UserID时才返回TRUE.如果表中不存在UserID，我希望它返回FALSE.

And it only returns TRUE if the UserID exists on the table. I want it to return FALSE if the UserID doesn't exist on the table.

推荐答案

如果用户不存在，那么您所拥有的将根本不会返回任何行.这就是您需要的:

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

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