在 PHP 脚本中插入 MySQL 数据库之前检查值是否存在

Question

I've looked for similar questions with no success.

I have this piece of code:

form1.php

$query  = "INSERT INTO table1 ";
$query .= "(fname, lname, mail)";
$query .= " VALUES ";
$query .= "('".$_POST[fname]."', '".$_POST[lname]."', '".$_POST[mail]."')"; 

$result = mysql_query($query) or die ("Query Failed: " . mysql_error());

And I want that the script will check if the value inserted exists in the corresponding column, and throw an error if it does. any ideas?

Answer 1

在您关心的字段上创建一个 UNIQUE 键，并在事后检测完整性错误。