MySQLi等同于MySQL代码 [英] MySQLi Equivalent Of MySQL Code

问题描述

您能给我相当于MySQLi的这段代码吗?无法正确处理.

Can you give me the equivalent of this code im MySQLi? Can't get it right.

<?php
if(mysql_num_rows(mysql_query("SELECT userid FROM users WHERE userid = '$userid'"))){
//code to be exectued if user exists
} 
?>

编辑:请向我解释一下哪里出了问题?

Care to explain to me what is wrong?

$mysqli = new mysqli($host, $username, $pass, $db);

if ($mysqli->connect_error) {
    die('The Server Is Busy. Please Try Again Later.');
}
$result = $mysqli->query("SELECT userid FROM users WHERE userid = '$userid'");
if ($result->num_rows) {
    echo "<h1>AWESOME</h1>";
}

推荐答案

从面向对象的意义上讲，它应来自:

Well, in an OO sense, it would go from:

if(mysql_num_rows(mysql_query("SELECT userid FROM users WHERE userid = '$userid'"))){
    //code to be exectued if user exists
}

收件人(假设数字用户名):

To (assuming numeric userid):

$result = $mysqli->query("SELECT userid FROM users WHERE userid = ".(int) $userid);
if ($result->num_rows) {
    //code
}

到(假设字符串用户标识):

To (assuming string userid) :

$result = $mysqli->query("SELECT userid FROM users WHERE userid = '". $db->real_escape_string($userid) . "');
if ($result->num_rows) {
    //code
}

至(假设准备好的语句):

To (assuming prepared statements) :

$stmt = $mysqli->prepare("SELECT userid FROM users WHERE userid = ?");
$stmt->bind_param('s', $userid);
$stmt->execute();
$stmt->store_result();
if ($stmt->num_rows) {
    //code
}

现在，假设您正在使用MySQLi的OOP版本(恕我直言，您应该使用它，因为它在许多方面都使生活更轻松).

Now, that's assuming you're using the OOP version of MySQLi (which you should be, IMHO, since it makes life easier in a lot of ways).

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