重复行MySQL

Question

嘿，我正在使用这样的查询：

INSERT INTO likes( 
         likes_memory_id, 
         likes_comment_id, 
         likes_owner_id, 
         likes_like
 ) VALUES (
         :likes_memory_id, 
         :likes_comment_id, 
         :likes_owner_id, 
         :likes_like)

当用户单击“赞”按钮时，此查询会添加一个新行。所以这个查询允许喜欢多次。为了防止这种情况，我可以使用一个select语句，我可能会在两个查询中成功，但我认为有一个更好的方法来做到这一点。 （我研究过如果不存在声明，但我不太了解）我如何避免多重喜欢？

Answer 1

最简单的方法是在列上创建一个您想要唯一的唯一索引;

CREATE UNIQUE INDEX uq_mem_own ON likes(
 likes_memory_id, likes_owner_id
);

...并使用INSERT IGNORE插入喜欢的内容，如果索引没有阻止它将插入值，否则只是忽略它;

INSERT IGNORE INTO likes( 
 likes_memory_id, 
 likes_owner_id, 
 likes_like
 ) VALUES (
 :likes_memory_id, 
 :likes_owner_id, 
 :likes_like)

Answer 2

INSERT INTO likes( 
     likes_memory_id, 
     likes_comment_id, 
     likes_owner_id, 
     likes_like
SELECT * 
FROM (:likes_memory_id, :likes_comment_id, :likes_owner_id ,:likes_like) tmp
WHERE NOT EXISTS ( SELECT * 
                   FROM `likes` 
                   WHERE `likes_memory_id` =  :likes_memory_id
                     AND `likes_comment_id` = :likes_comment_id
                     AND `likes_owner_id` = :likes_owner_id
                     AND `likes_like` = :likes_like
                 ) LIMIT 1;

Answer 3

You can accomplish this either disable like button after hit or 
using the following query

     INSERT INTO likes 
             (likes_memory_id, 
              likes_comment_id, 
              likes_owner_id, 
              likes_like)
SELECT t1.likes_owner_id
FROM likes t1
WHERE NOT EXISTS(SELECT likes_owner_id
                FROM likes t2
               WHERE t2.likes_owner_id = t1.likes_owner_id);

and make sure that your likes_owner_id is primary or a unique key 

Answer 4

好问题！您可以简单地收集用户的IP地址，如果该用户尝试“喜欢”两次，则不会记录。

步骤1：创建一个名为IP（或任何你喜欢的）的新列[这将用于收集用户IP地址。）

步骤2：将IP设置为PRIMARY KEY（这是防止重复输入的内容）

第3步：将其添加到您的查询中。

INSERT INTO likes( 
         IP,
         likes_memory_id, 
         likes_comment_id, 
         likes_owner_id, 
         likes_like
 ) VALUES (
         :IP,
         :likes_memory_id, 
         :likes_comment_id, 
         :likes_owner_id, 
         :likes_like)

步骤4：现在您要做的就是添加一行代码来收集用户IP并将其与其他信息一起提交。