我能有这样的东西吗?
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 |
+---------+
仅当查询中没有选择行时:
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0行!这可能吗?
SELECT 1
FROM dual
WHERE NOT EXISTS
(
SELECT NULL
FROM mytable
WHERE id = 1
)
查询:
SELECT CASE
WHEN COUNT(id) = 0 THEN 1
ELSE 0
END AS Available
FROM `TABLE`
WHERE id = 1