Mysql查询忽略NULL和空字段

Question

我有一个非常疯狂的查询，我知道，但是当我运行它时，它会返回所有匹配，无论是否为空的mvideo是否为空。

查询是：

SELECT * 
FROM `weaponsprojects` 
WHERE mvideo != "" 
    AND credit7 = "' .$person. '" 
    OR credit2 = "' .$person. '" 
    OR credit3 = "' .$person. '" 
    OR credit4 = "' .$person. '" 
    OR credit5 = "' .$person. '" 
    OR credit6 = "' .$person. '" 
    OR credit1 = "' .$person. '" 
    OR credit8 = "' .$person. '" 
    OR credit9 = "' .$person. '" 
    OR credit10 = "' .$person. '" 
    OR credit11 = "' .$person. '" 
    OR credit12 = "' .$person. '" 
    ORDER BY usort' 

，并返回当任何学分等于人，但它完全忽略了mvideo部分。为什么是这样？？

编辑：字段不为空，只是单纯的空没有空格只是空白

Answer 1

我认为WHERE条件在逻辑上是有缺陷的......你在这里需要一些优先级，例如：

SELECT * 
FROM `weaponsprojects` 
WHERE mvideo != "" 
    AND (credit7 = "' .$person. '" 
    OR credit2 = "' .$person. '" 
    OR credit3 = "' .$person. '" 
    OR credit4 = "' .$person. '" 
    OR credit5 = "' .$person. '" 
    OR credit6 = "' .$person. '" 
    OR credit1 = "' .$person. '" 
    OR credit8 = "' .$person. '" 
    OR credit9 = "' .$person. '" 
    OR credit10 = "' .$person. '" 
    OR credit11 = "' .$person. '" 
    OR credit12 = "' .$person. '") 
    ORDER BY usort' 

通过添加(和)我们告诉WHERE声明：“无论是mvideo是不是空的，它匹配OR语句之一”