使用php mysqli检查电子邮件是否存在

Question

I am new to mysqli i wanted to check if email already exists in database with php and mysqli

Here is what i have done so far:

ini.php

<?php
session_start();
require 'connect.php';
include 'user.func.php'; 
?>

connect.php

<?php
$con = new mysqli('host', 'user', 'password', 'db');
if($con->connect_errno > 0){
die('Sorry, We\'re experiencing some connection problems.'); 
}

?>

register.php

<?php
include 'ini.php';
?>

<form action="" method="post">
<p>Username:<br/><input type="text" name="reg_name" maxlength="50"  ></p>
<p>Email:<br/><input type="text" name="reg_email" size="35" maxlength="50"  ></p>
<p>Password:<br/><input type="password" name="reg_password" maxlength="50" ></p>
<p>Re-type Password:<br/><input type="password" name="reg_re_password" maxlength="20"></p>
<p><input type="submit" value="Register" ></p>
</form>

<?php
include 'validate.php';
?>

validate.php

<?php
if(isset ( $_POST['reg_name'],$_POST['reg_email'], $_POST['reg_password'] )) {

$errors = array();
$name = $_POST['reg_name'];
$email = $_POST['reg_email'];
$password = $_POST['reg_password'];
$re_password = $_POST['reg_re_password'];
if(empty($name) || empty($email) || empty($password) || empty($re_password)){
$errors[] = 'All fields are required';
 } else {

if(strlen($name) > 50 || strlen($email) > 50 || strlen($password) > 50) {
 $errors[] = 'One or more field has too long Characters';
}

if(filter_var($email, FILTER_VALIDATE_EMAIL) === FALSE && $password !== $re_password){
$errors[] = 'Enter valid email address and password do not match';
}else{

if(filter_var($email, FILTER_VALIDATE_EMAIL) === FALSE) {
$errors[] = 'Please enter a valid email address';
}

if($password !== $re_password){
$errors[] = 'Both passwords do not match';
}
if(user_exists($email) > 0){
$errors[] = 'That email is already been registered';
}

}

}

if (!empty($errors)) {
foreach ($errors as $errors) {
    echo '<strong>',$errors,'</srtong><br />';
}
}else{
echo 'Registered';
}
}

?> user.func.php

<?php    
function user_exists($email) {

$con = new mysqli('host', 'user', 'password', 'db');
$query = "SELECT * FROM users WHERE email = ?";
$stmt = $con->prepare($query);
$stmt->bind_param("s", $email);

if ($stmt->execute()) {
return $stmt->num_rows;
}
return false;
}
?>

This code shows all the other errors but doesn't check if the email exist. Instead it shows registered even when i enter email that is already in database.

I have database named 'test'. And table 'users' with columns user_id, username, email and password.

Can anyone tell how to code mysqli query for this?

I used this code in mysql

function user_exists($email) {
$email = mysql_real_escape_string($email);
$query = mysql_query("SELECT COUNT('user_id') FROM 'users' WHERE 'email'='$email'");
return (mysql_result($query, 0) == 1) ? true :false;
}

Answer 1

Use this condition, because you are returning the number of rows from your query.

if(user_exits($register_email) > 0){

Edit

function user_exists($email) {
    $mysqli = new mysqli("host", "my_user", "my_password", "your_db");
    $query = "SELECT COUNT(*) AS num_rows FROM users WHERE email = ?";
    $stmt = $mysqli->prepare($query);
    $stmt->bind_param("s", $email);

    if ($stmt->execute()) {
        return $stmt->num_rows;
    }
    return false;
}

Answer 2

I could tell how to do it with PDO

<?php
function user_exists($email) {
    $query = "SELECT 1 FROM " . USER_TABLE . " WHERE email = ?";
    $stmt = $this->_db->prepare($query);
    $stmt->execute(array($email));
    return (bool)$stmt->fetchColumn();
}

Though I see no point in strict checking

if(user_exits($register_email))

would be more than enough

Also, I don't understand where did you get that $register_email variable. Do you have error reporting on?

By the way, you need an established PDO connection for this. This code won't work with mysqli