Mysql查詢忽略NULL和空字段

Question

我有一個非常瘋狂的查詢，我知道，但是當我運行它時，它會返回所有匹配，無論是否爲空的mvideo是否爲空。

查詢是：

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' 

，並返回當任何學分等於人，但它完全忽略了mvideo部分。爲什麼是這樣？？

編輯：字段不爲空，只是單純的空沒有空格只是空白

Answer 1

我認爲WHERE條件在邏輯上是有缺陷的......你在這裏需要一些優先級，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' 

通過添加(和)我們告訴WHERE聲明：「無論是mvideo是不是空的，它匹配OR語句之一」