Question

我正在尝试从我的所有数据库表中获取我在Web服务器上运行的脚本的电子邮件。不幸的是，某些表中有一些重复的电子邮件。这应该是一个简单的解决方案，使用SELECT DISTINCT，INSERT IGNORE等，但似乎没有任何工作。

这是我目前的查询：

CREATE TEMPORARY TABLE `all_emails` (
     id int(10) unsigned NOT NULL AUTO_INCREMENT,
     email VARCHAR(80) NOT NULL,
     ip_address VARCHAR(20) NOT NULL,
     PRIMARY KEY (id),
     UNIQUE INDEX(email)
);

INSERT IGNORE INTO `all_emails` (email, ip_address)  
SELECT email,IP_address
  FROM `table_1_emails`
 WHERE unsubscribed_at IS NULL;

INSERT IGNORE INTO `all_emails` (email, ip_address)  
SELECT email,ip_address
  FROM `table_2_emails`
 WHERE unsubscribed_at IS NULL;

INSERT IGNORE INTO all_emails (email, ip_address)  
SELECT email,ip_address
  FROM `table_3_emails`;

INSERT IGNORE INTO `all_emails` (email, ip_address)  
SELECT email,ip_address
  FROM `table_4_emails`;

SELECT DISTINCT email, ip_address, id FROM `all_emails`;

这仍会产生重复的电子邮件。

Answer 1

只需使用UNION即可删除单个INSERT中的重复项：

INSERT IGNORE INTO `all_emails` (email, ip_address)  
SELECT email,IP_address
  FROM `table_1_emails`
 WHERE unsubscribed_at IS NULL
UNION
SELECT email,ip_address
  FROM `table_2_emails`
 WHERE unsubscribed_at IS NULL
UNION
SELECT email,ip_address
  FROM `table_3_emails`
UNION
SELECT email,ip_address
  FROM `table_4_emails`;

MySQL - 独特且不同的值不起作用

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