mysqli 插入 - 但前提是不重复

2021-12-25 00:00:00 search insert php mysql mysqli

我是一名 Java 开发人员，刚刚完成了一些快速简单的数据库工作"的任务——除了我对 PHP/MySQL 不太了解……我需要将记录插入到数据库中——但只有如果电子邮件字段与数据库中已存在的字段不匹配.到目前为止，我收集到的 PHP 代码如下:

I'm a Java developer who just got handed the task of "some quick easy DB stuff" - except I don't know much about PHP/MySQL...I need to insert a record into a DB - but only if the email field doesn't match one that already exists in the DB. Here's what I've gleaned so far for my PHP code:

// Grab the values from the HTML form:
$newUserName = $_POST['newUserName'];
$newUserName = $mysqli->real_escape_string($newUserName);
$newUserEmail = $_POST['newUserEmail'];
$newUserEmail = $mysqli->real_escape_string($newUserEmail);

// Now search the DB to see if a record with this email already exists:
$mysqli->query("SELECT * FROM RegisteredUsersTable WHERE UserEmail = '$newUserEmail'");

现在我需要查看是否有任何内容从该搜索中返回 - 这意味着电子邮件已经存在 - 如果是，我需要提醒用户，否则我可以继续使用:

Now I need to see if anything came back from that search - meaning the email already exists - and if so I need to alert the user, otherwise I can go ahead and insert the new info into the DB using: 

$mysqli->query("INSERT INTO RegisteredUsersTable (UserName, UserEmail) VALUES ('".$newUserName."', '".$newUserEmail."')");

有什么想法吗?

推荐答案

根据您的代码工作，这应该为您指明正确的方向.也许有更好的方法来构建您的数据库，以便更好地利用它.

Working from your code, this should point you in the right direction. there are, perhaps, better ways to structure your database that will make better use of it.

<?php

$mysqli = new mysqli("localhost", "iodine", "iodine","iodine");

// Grab the values from the HTML form:
/*
$newUserName = $_POST['newUserName'];
$newUserName = $mysqli->real_escape_string($newUserName);
$newUserEmail = $_POST['newUserEmail'];
$newUserEmail = $mysqli->real_escape_string($newUserEmail);
*/
$newUserName = "Test User";
$newUserEmail = "test4@example.com";

// Now search the DB to see if a record with this email already exists:
echo "SELECT * FROM RegisteredUsersTable WHERE UserEmail = '$newUserEmail'", "
";
$result = $mysqli->query("SELECT * FROM RegisteredUsersTable WHERE UserEmail = '$newUserEmail'");

if (!$result) {
  die($mysqli->error);
}
echo "num_rows = ".$result->num_rows."
";
if ($result->num_rows > 0) {
   echo "Duplicate email
";
   // do something to alert user about non-unique email
} else {
  $result = $mysqli->query("INSERT IGNORE INTO RegisteredUsersTable (UserName, UserEmail) VALUES ('".$newUserName."', '".$newUserEmail."')");
  if ($result === false) {echo "SQL error:".$mysqli->error;}
}

?>

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