我总是假设以下形式的陈述
SELECT * FROM A LEFT JOIN B ON (A.column1 = B.column2 AND B.column2 = 12321)
总是等价于
SELECT * FROM A LEFT JOIN B ON (A.column1 = B.column2)
WHERE B.column2 = 12321
更笼统地说：
SELECT * FROM A LEFT JOIN B ON (FOREIGN-KEY AND FILTER_ON(B))
WHERE FILTER_ON(A)
应该相当于
SELECT * FROM A LEFT JOIN B ON (FOREIGN-KEY)
WHERE FILTER_ON(A) AND FILTER_ON(B)
情况似乎并非如此...第一种类型提供的结果行数比第二种类型多。
问题：在哪些情况下我的假设是错误的？