mysqli insert-但仅当不是重复项时 [英] mysqli insert - but only if not a duplicate

问题描述

我是一名Java开发人员，刚刚完成了一些快速简单的DB任务"的任务-除非我对PHP/MySQL不太了解...我需要在DB中插入记录-但仅如果电子邮件字段与数据库中已存在的电子邮件字段不匹配.到目前为止，这是我为我的PHP代码所收集的内容:

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，我需要查看搜索是否返回了任何内容-意味着电子邮件已经存在-如果需要，我需要提醒用户，否则，我可以继续使用以下命令将新信息插入数据库:

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

从您的代码开始，这应该为您指明正确的方向.也许有更好的结构来更好地利用数据库.

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 = "[e-mail]";

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

if (!$result) {
  die($mysqli->error);
}
echo "num_rows = ".$result->num_rows."\n";
if ($result->num_rows > 0) {
   echo "Duplicate email\n";
   // 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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