按复合索引查询SQL

Question

我们假设我有一个items列id type number room，id是主键， (type, number)是一个独特的复合键;列inventory，id，item_type，item_number，owner的表格id是主键，(type, number)是独特的复合键。

示例：

items

| id | type    | number | room |
+----+---------+--------+------+
|  1 |  laptop |      1 |   12 |
|  2 |  laptop |      2 |   13 |
|  3 | desktop |      1 |   13 |

inventory

| id | item_type | item_number | owner |
+----+-----------+-------------+-------+
|  1 |    laptop |           1 |   Joe |
|  2 |    laptop |           2 |   Joe |
|  3 |   desktop |           1 | Susan |

如何查询Joe拥有的所有items？如果我做

SELECT *
FROM items
WHERE (type, number) IN (
    SELECT item_type, item_number FROM inventory WHERE owner = 'Joe'
)

我只在结果中获得一行，但子查询返回多行。我似乎无法在多列上执行join，例如

SELECT *
FROM items
JOIN inventory ON inventory.item_type = items.type,
    inventory.item_number = items.number`
WHERE inventory.owner = 'Joe'

Answer 1

您应该将连接条件与AND组合，而不是用逗号组合。