如果值为零，请不要检查where语句？

Question

我想检查一个值是否与另一个值匹配，但仅在该值不为零时才检查。前两个例子将在where语句中考虑，但不在第三个例子中考虑。我试图看看if语句是否有效，但我不知道从哪里开始。

SELECT `books`.* FROM `books` 
LEFT JOIN issues ON issues.id = books.issue_id 
LEFT JOIN titles ON titles.id = issues.title_id
LEFT JOIN lists ON books.id = lists.book_id 
WHERE ( lists.customer_id = '900001' 
AND lists.volume = issues.volume AND `books`.`status_id` = '3' 
AND `books`.`deleted` = "0" ) 
GROUP BY `books`.`id`

以下是mysql查询的示例：

{{1}}

因此，如果lists.volume = 0，我不希望在where语句中检查它。

Answer 1

select column1, column2, if (column1 = column2, 'match', 'not matched') matched
from x
where column1 <> 0 and column2 <> 0