php - MySQL 错误 : 'Unkown column' tablename. 列名在 'on clause'

Question

我正在尝试将 2 个表连接到另一个表。我有这个 SQL 查询:

SELECT
desc_1.description,
desc_2.description,
Object.objID,
Item.itemID
FROM
Object,
Item 
INNER JOIN Foo desc_1 ON desc_1.descID = Object.objDescID
INNER JOIN Foo desc_2 ON desc_2.descID = Item.itemDescID;

但是我收到以下错误:

ERROR 1054: Unkown column 'Object.objDescID' in 'on clause'

期望的输出:

description | description | objID | itemID |
------------+-------------+-------+--------+      
 "Daughter" |   "Shoes"   |   20  |   25   |

有谁知道为什么会这样吗？该列存在于表中，我已检查拼写等。

Answer 1

您不能混合使用旧的隐式连接语法和显式连接语法。使用

SELECT desc_1.description,
       desc_2.description,
       Object.objID,
       Item.itemID
FROM Object
INNER JOIN Item on { fill in the column that relate object and item }
INNER JOIN Foo desc_1 ON desc_1.descID = Object.objDescID
INNER JOIN Foo desc_2 ON desc_2.descID = Item.itemDescID;