Mysqli 预处理语句寄存器

Question

好的，我有一个问题。我需要检查用户是否已经存在，但现在的问题是我需要在 if() 中输入什么我无法获取，因为我已经关闭，但如果我没有关闭，我会收到错误消息，因为不能' t 运行 2 条语句。所以我想是否有人可以帮助我？我有其余的代码，但我只在这里给出代码。

这是我的代码：

$result = $mysqli->prepare("SELECT username FROM user WHERE username=?");
$result->bind_param("s", $username);
$result->execute();
$result->bind_result($username);                                
$result->close();

if (){
$register = $mysqli->prepare("INSERT INTO user 
                    (username, password, email, rr, rank) 
                     VALUES (?, ?, ?, ?, ?)");
$register->bind_param("sssii", $username, $kode, $email, $rr, $rank);
$register->execute();
$register->close();                                 
} else {
    echo "User already exists!";
}

Answer 1

更新：更合乎逻辑的陈述

$result = $mysqli->prepare("SELECT username FROM user WHERE username=?");
$result->bind_param("s", $username);
$result->execute();
$found = $result->fetch();                        
$result->close();

if ($found){        
    echo "User already exists!";                                          
} else {
    $register = $mysqli->prepare("INSERT INTO user 
                    (username, password, email, rr, rank) 
                     VALUES (?, ?, ?, ?, ?)");
    $register->bind_param("sssii", $username, $kode, $email, $rr, $rank);
    $register->execute();
    $register->close(); 

}

Mysqli 预处理语句寄存器

Mysqli prepared statements register

php

mysqli

fetch

statements