查找哪些电子邮件在同一列表中不同的表但列名相同的电子邮件地址

Question

我有 11 张桌子

email1,email2,email3,email4,email5,email6,email7,email8,email9,email10,email11

和相同的列名 Contact_Email 不同的电子邮件地址

<?php
    $con = mysql_connect("localhost","root","");
    $db = mysql_select_db("email-db",$con);

    $sql = "SELECT Contact_Email FROM email1,email2,email3,email4";
    $result = mysql_query($sql);
    while($row = mysql_fetch_array($result)) {
    ?>
    <tr>
      <td><? echo $row['Contact_Email']; ?></td>
      <td><? echo '<br>'; ?></td>
    </tr>
    <? } ?>

实际上我想要这个输出

select all emails from all tables using join foreach emails as email check if email is in table 1, if yes put yes in td check if email is in table 2, if yes put yes in td check if email is in table 3, if yes put yes in td

等等

请帮帮我，我该怎么办？

Answer 1

只需使用 UNION，如下例所示：

SELECT u.email
FROM email1 AS u
UNION 
SELECT e.email
FROM email2 AS e

在PHP中：

$sql = "SELECT u.email FROM email1 AS u 
UNION SELECT e.email FROM email2 AS e";
$result = mysql_query($sql);while($row = mysql_fetch_array($result))
 { ...}

为避免MYSQL错误"Illegal mix of collations for operation 'UNION'"请同步所有电子邮件字段以具有相同的参数

查找哪些电子邮件在同一列表中不同的表但列名相同的电子邮件地址

Fatch which emails are on the same lists different tables but same column name email addressess

php

mysql

join

inner-join