从列表中选择不在表格中的值

Question

我有一个 id 列表：

(1, 2, 3, 6, 7)

还有一张桌子：

id | anothercolumn
------------------
 1 | NULL
 2 | foo
 4 | bar
 5 | NULL
 6 | NULL

我想从我的列表中检索不是我的表的 id 的值。

预期结果：

3, 7

不带 FROM 的选择

我尝试过这样的事情：

SELECT i
WHERE i IN (1, 2, 3, 6, 7)
AND i NOT IN (SELECT id FROM mytable);

但这不是一个有效的 MySQL 查询（FROM 是必需的）。

联合

也有这种可能：

SELECT i
FROM (
    SELECT 1 AS i
    UNION SELECT 2
    UNION SELECT 3
    UNION SELECT 6
    UNION SELECT 7 ) AS mylistofids
LEFT JOIN mytable
ON mytable.id = i
WHERE mytable.id IS NULL;

这行得通，但是如果我的 id 列表变大，查询很快就会变大......

临时表

我还可以为我的 id 列表创建一个临时表：

CREATE TEMPORARY TABLE mylistofids (
    i INT
);

INSERT INTO mylistofids (i) VALUES (1), (2), (3), (6), (7);

然后在LEFT JOIN中使用它：

SELECT i
FROM mylistofids
LEFT JOIN mytable
ON mytable.id = i
WHERE mytable.id IS NULL;

这也有效，但就我而言，我无权创建表（临时或非临时）。

您是否找到了以最好的方式解决此问题的方法？

Answer 1

临时表是最好的解决方案，但如果不可能，那么您可以通过选择常量并将它们联合在一起来伪造临时表。

使用此解决方案，您可以执行以下操作：-

SELECT i
FROM 
(
    SELECT 1 AS i UNION SELECT 2 UNION SELECT 3 UNION SELECT 6 UNION SELECT 7
) AS mylistofids 
LEFT JOIN mytable
ON mytable.id = i
WHERE mytable.id IS NULL;

您还可以通过交叉连接数字范围来生成大量数字（假设您正在处理整数 id）。然后只需选择 IN 子句中的那些：-

SELECT i
FROM 
(
    SELECT units.i + tens.i * 10 + hundreds.i * 100 + thousands.i * 1000 + tensthousands.i * 10000 AS i
    FROM (SELECT 1 AS i UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9 UNION SELECT 0 ) AS units
    CROSS JOIN (SELECT 1 AS i UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9 UNION SELECT 0 ) AS tens
    CROSS JOIN (SELECT 1 AS i UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9 UNION SELECT 0 ) AS hundreds
    CROSS JOIN (SELECT 1 AS i UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9 UNION SELECT 0 ) AS thousands
    CROSS JOIN (SELECT 1 AS i UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9 UNION SELECT 0 ) AS tensthousands
) AS mylistofids 
LEFT JOIN mytable
ON mytable.id = i
WHERE mylistofids.i IN (1, 2, 3, 6, 7)
AND mytable.id IS NULL;