php - Mysql查询忽略NULL和空字段

Question

我知道我有一个非常疯狂的查询，但是当我运行它时它会返回所有匹配项，无论字段 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'

它会在任何一个点数等于这个人时返回，但它会完全忽略 mvideo 部分。这是为什么？？

编辑:该字段不是 NULL，只是简单地留空，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......你需要在这里有一些优先级，就像这样:

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 语句:“要么 mvideo 不为空并且它匹配 OR 语句之一”