如何避免重复的电子邮件php/sql？

我用这个代码，我不知道是什么问题，我使用了不同的代码以及如何避免重复的电子邮件php/sql？

什么我想要做的检查，不允许用户添加他的邮件两次

<?php 
include("includedb.php"); 
//declare variables 
$name  = $_POST['name']; 
$email  = $_POST['email']; 
$tel   = $_POST['tel']; 
$gift  = $_POST['gift']; 
$formName = $_POST['formName']; 
$formEmail = $_POST['formEmail']; 
$formEmirate = $_POST['formEmirate']; 
$birthday = $_POST['birthday']; 
$date  = $_POST['date']; 

$result = mysqli_query("SELECT * FROM users WHERE email = '$email'") or exit(mysqli_error()); //check for duplicates 

$num_rows = mysqli_num_rows($result); //number of rows where duplicates exist 

if ($num_rows == 0) { //if there are no duplicates...insert 
    $sql = "INSERT INTO users (name, email, tel, gift, formName, formEmail, formEmirate, birthday, date) 
VALUES ('$name', '$email', '$tel','$gift', '$formName', '$formEmail', '$formEmirate','$birthday',CURRENT_TIMESTAMP)"; 
    if (!mysqli_query($sql)) { 
     die('Error: ' . mysqli_error()); 
    } 
} 

mysqli_close(); 

header("location: thank-you.html?remarks=success"); 

?>

来源

2017-08-16 developer91

的数据库您使用 –

你的逻辑似乎很动听，什么exactely是不使用该代码？顺便说一下，你可以开放SQL注入，请阅读。 :) – xander

'if（$ num_rows == 0）{...} else {$ sql =“UPDATE ...”} –

感谢支持我找到了曾与我一起工作，请看看下面的代码，请告诉我如何，以确保安全并保护其免受SQL注入

if(isset($_POST['submit'])){ 
$name= $_POST['name']; 
$email= $_POST['email']; 


$result = mysqli_query($conn,"SELECT * FROM test WHERE email = '$email'") or exit(mysqli_error()); //check for duplicates 
$num_rows = mysqli_num_rows($result); //number of rows where duplicates exist 

if(($num_rows) > 0){ 
    echo "A record already exists."; 
    exit; 
    } 

else{ 
$sql = "INSERT INTO test (name, email) 
VALUES ('$name', '$email')"; 
if (!mysqli_query($conn,$sql)) 
    { 
    die('Error: ' . mysqli_error()); 
    } 
} 

if($result) { 

      header("Location: game.html"); 

}else{ echo "Not Successful"; } 

mysqli_close(); 
} 
?> 

<!DOCTYPE html> 
<head> 

</head> 
<body> 

<h2>Enter your Name and Email</h2> 
<form method="post"> 
    <p><strong>First Name:</strong><br /> <input type="text" name="name" /></p> 
    <p><strong>email:</strong><br /> <input type="email" name="email"/></p> 

    <input type="submit" name="submit" value="Add Customer" /> 
</form> 



</body> 
</html>

来源

2017-08-17 11:44:14 developer91

问题是你不能传递任何连接请求mysql_query

这样的疑问没有得到查询

$conn = your connection; 

$result = mysqli_query($conn,"SELECT * FROM users WHERE email = '$email'") or exit(mysqli_error()); //check for duplicates 
$num_rows = mysqli_num_rows($result); //number of rows where duplicates exist 
if($num_rows == 0) { //if there are no duplicates...insert 
$sql = "INSERT INTO users (name, email, tel, gift, formName, formEmail, formEmirate, birthday, date) 
VALUES ('$name', '$email', '$tel','$gift', '$formName', '$formEmail', '$formEmirate','$birthday',CURRENT_TIMESTAMP)"; 
if (!mysqli_query($conn,$sql)) 
    { 
    die('Error: ' . mysqli_error()); 
    } 
}

来源

2017-08-16 09:13:43 Exprator

嗨，感谢您的帮助，但仍然得到空白页 $ result = mysqli_query（$ conn，“SELECT * FROM users WHERE email ='$ email'”）或exit（mysqli_error（）） ; $ num_rows = mysqli_num_rows（$ result）; 如果（$ num_rows == 0）{ $ sql =“INSERT INTO用户（名称，电子邮件，电话，礼物，formName，formEmail，formEmirate，生日，日期） VALUES（'$ name'，'$ email'， '$ tel'，'$ gift'，'$ formName'，'$ formEmail'，'$ formEmirate'，'$ birthday'，CURRENT_TIMESTAMP）“;如果（！mysqli_query（$ conn，$ sql）） { die（'Error：'。mysqli_error（））; } } – developer91

如何避免重复的电子邮件php/sql？

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