MySQL 1054錯誤 Unknown column .... in 'on clause'

[Err] 1054 - Unknown column 'o.ordersId' in 'on clause'

解決方法：將from后面的表用()來。

例：

SELECT a.id, b.id, c.id FROM A a, B b LEFT JOIN C c ON c.a_id = a.a_id AND c.b_id = b.b_id  

這句話在mysql5下執行會有問題，要把聯合的表用括號包含起來才行：

SELECT a.id, b.id, c.id) FROM (A a, B b) LEFT JOIN C c ON c.a_id = a.a_id AND c.b_id = b.b_id  

這樣就可以執行了、