Question

示例：

表A

id
1
2
3

表B

id        value     fk_a
1          -5        1
2          -7        1
3           5        2
4          -10       3
5          20        3

表A-> id 1的所有子表列（值）均为负数

Answer 1

您可以使用ALL

PostgreSQL和Oracle的有效查询

 select * from A
 where id = ALL (select fk_a from B where value < 0 and fk_a = id)

 select * from A
 where id <> ALL (select fk_a from B where `value` > 0 and fk_a = A.id)

MySQL的有效查询

select * from A
where id <> ALL (select fk_a from B where `value` > 0 and fk_a = A.id)

Working Fiddle

Answer 2

我将使用子查询获取具有正值的条目的FK ID，然后使用该查询的结果通过WHERE NOT IN子句在主查询中进行过滤

模式（MySQL v5.7）

CREATE TABLE A (
  `id` INTEGER PRIMARY KEY
);

INSERT INTO A
  (`id`)
VALUES
  (1),
  (2),
  (3);

CREATE TABLE B (
  `id` INTEGER,
  `value` INTEGER,
  `fk_a` INTEGER,
  FOREIGN KEY (fk_a) REFERENCES A (id)
);

INSERT INTO B
  (`id`, `value`, `fk_a`)
VALUES
  (1, -5, 1),
  (2, -7, 1),
  (3, 5, 2),
  (4, -10, 3),
  (5, 20, 3);

查询＃1

SELECT * FROM A
WHERE A.id NOT IN
(
  SELECT tb.fk_a
  FROM B tb
  WHERE tb.`value` >= 0
);

输出

| id  |
| --- |
| 1   |

View on DB Fiddle

如何在SQL中检查子表所有列值是否为负

2 个答案: