mysql - 爲什麼sql查詢選擇不必要的值？

Question

我想選擇條件爲true的行。我有一個名爲command的列，如果列值包含已定義的（由我）字符串，則添加到結果中。

我的問題是選擇行，因爲查詢沒有看到WHERE語句，所以如果列command包含字符串，它會選擇所有數據。

SELECT * 
FROM `admin_log` 
WHERE `admin_log`.`user` = 'Admin' 
    AND command LIKE '%aznot%' 
    OR command LIKE '%hango%' 
ORDER BY `order_id` DESC 
LIMIT 0, 50 

例如，我有3個管理員帳戶：Admin，Zuppa，Grund。如果命令列包含：aznot或hango，我希望通過帳戶ADMIN選擇所有數據。

我在做什麼錯？

Answer 1

你需要一些括號。

SELECT * 
FROM `admin_log` 
WHERE `admin_log`.`user` = 'Admin' 
AND (command LIKE '%aznot%' OR command LIKE '%hango%') 
ORDER BY `order_id` 
DESC LIMIT 0, 50 

Answer 2

SELECT * FROM `admin_log` WHERE `admin_log`.`user` = 'Admin' 
AND (command LIKE '%aznot%' OR command LIKE '%hango%') 
ORDER BY `order_id` DESC LIMIT 0, 50 

Answer 3

嘗試是這樣的：

SELECT * FROM `admin_log` WHERE `admin_log`.`user` = 'Admin' AND (command LIKE '%aznot%' OR command LIKE '%hango%') ORDER BY `order_id` DESC LIMIT 0, 50 

Answer 4

這是更好的做法是分離或報表到一個單獨的表達，防止誤解發動機。

SELECT * FROM `admin_log` WHERE `admin_log`.`user` = 'Admin' AND (command LIKE '%aznot%' OR command LIKE '%hango%') ORDER BY `order_id` DESC LIMIT 0, 50 

Answer 5

SELECT * 
FROM `admin_log` 
WHERE `admin_log`.`user` = 'Admin' 
     AND (command LIKE '%aznot%' 
     OR command LIKE '%hango%') 
ORDER BY `order_id` DESC 
LIMIT 0, 50 

Answer 6

您需要正確巢的條件。請參閱SQL中邏輯運算符的優先級規則