MySQL 检查用户是否存在> 0 - mysql check if user exist > 0

mysql check if user exist > 0

本文关键字：存在检查用户是否 MySQL | 更新日期: 2023-09-27

$check_select = mysql_num_rows(mysql_query("SELECT * FROM `fblogin` WHERE email = '$user_email'")); 
if($check_select > 0)
    mysql_query("INSERT INTO `fblogin` (fb_id, name, email, image, postdate) VALUES ('$user_fbid', '$user_fnmae', '$user_email', '$user_image', '$now')");

我

从网上某处获取的代码，我只是好奇它是否正确if($check_select > 0)，我认为它应该是if($check_select != 0)的，对吧？

上面的代码将起作用，如果基本上是说$check_user是否高于0，这与说如果$check_user不等于0相同。

我以前使用过这段代码，这是我用它做的：

这是基于您是否要创建新用户

您必须在Mysql_query中连接到数据库，我建议使用 mysqli，而不是 mysql：

// CONNECT TO THE SERVER
$sql_con = mysqli_connect(host,username,password,dbname);
// RUN THE QUERY ON YOUR DATABASE
$check_user = mysqli_query($sql_con, "SELECT * FROM `fblogin` WHERE email = '$user_email'");
// GET NUMBER OF USERS FOUND
$check_user_num = mysqli_num_rows($check_user);
// IF NO USER EXISTS IN DATABASE DO THE FOLLOWING
if($check_user_num = 0) {
    mysql_query("INSERT INTO `fblogin` (fb_id, name, email, image, postdate) VALUES ('$user_fbid', '$user_fnmae', '$user_email', '$user_image', '$now')");
} else {
    // ELSE DO THIS CODE HERE (for me, I normally redirect with an error code, like the following:)
    header('location:?error=exists');
}

$conn=mysqli_connect("hostname","username","password");

$check_select = mysqli_query("SELECT * FROM `fblogin` WHERE email = '$user_email'"); 
$numrows=mysqli_num_rows($check_select);
if($numrows > 0){
    mysqli_query("INSERT INTO `fblogin` (fb_id, name, email, image, postdate) VALUES ('$user_fbid', '$user_fnmae', '$user_email', '$user_image', '$now')");
}