mysql - MySQL：SELECT IF() 语句中的 SELECT

Question

我可以有这样的东西吗？

SELECT IF((SELECT COUNT(id) FROM table WHERE id = 1) = 0, 1, <nothing_to_happen>) AS Available

我的目标是选择这个：

+---------+
|Available|
+---------+
|1        |
+---------+

仅当没有从此查询中选择行时：

SELECT id FROM table WHERE id = 1

如果表中存在 id = 1 的行，我希望我的查询返回零行！那可能吗？

Answer 1

SELECT  1
FROM    dual
WHERE   NOT EXISTS
        (
        SELECT  NULL
        FROM    mytable
        WHERE   id = 1
        )

Answer 2

询问：

SELECT CASE
           WHEN COUNT(id) = 0 THEN 1
           ELSE 0
       END AS Available
FROM `TABLE`
WHERE id = 1