如果单元格为空，则从数据库获取电子邮件不会提取 - Fetching emails from database don't fetch if cell is null empty

Fetching emails from database don't fetch if cell is null empty

我编写了一个代码来获取所有用户的电子邮件，然后将其保存在txt文件中，但有些用户没有和电子邮件，因为他们使用电话号码注册所以当我试图获取
时它在 txt 文件中转储，例如http://prntscr.com/5wf7cv

我想要如果单元格为空/空不获取任何内容任何人都可以帮助我修复它吗？

    $sql=mysql_query("SELECT * FROM user  "); 
    while($row = mysql_fetch_array($sql)) {
 $email = $row['email']   ;
  $fp = fopen("emaillist.txt", "a");
$savestring = "'n$email";
fwrite($fp, $savestring);
fclose($fp);
}
echo  "DONE ";

将查询更改为

SELECT * FROM user  WHERE email != NULL

SELECT * FROM user  WHERE email IS NOT NULL

检查 NULL 值的唯一方法是

column IS NULL或column IS NOT NULL

试试这个：

$sql=mysql_query("SELECT * FROM user  "); 
while($row = mysql_fetch_array($sql)) {

    if (strlen($row['email'] ) > 0){
        $email = $row['email'];
        $fp = fopen("emaillist.txt", "a");
        $savestring = "'n$email";
        fwrite($fp, $savestring);
        fclose($fp);
    }
}
echo  "DONE ";