MySQL：SELECT IF（）語句中的SELECT

Question

我能有這樣的東西嗎？

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

我的目標是選擇這個：

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

僅當此查詢中未選擇任何行時：

SELECT id FROM table WHERE id = 1

如果表中存在id = 1的行，我希望我的查詢返回零行！ 那可能嗎？

Answer 1

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

Answer 2

查詢：

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