php - 使用准备好的语句检查电子邮件是否已经在数据库中

Question

我正在尝试将我的代码更改为来自 mysql 的 msqli 准备语句。我不确定如何调整我目前可以检查数据库中是否已有电子邮件的代码。以下是我目前正在使用的有效代码。如何将其更改为准备好的语句并获得相同的结果？

//if email is equal to an email already in the database, display an error message

if(mysql_num_rows(mysql_query("SELECT * FROM users WHERE email = '".mysql_real_escape_string($_POST['email'])."'")))
{
  echo "<p class='red'>Email is already registered with us</p>";
} else {
  // missing code?
}

Answer 1

应该是这样的:

// enable error reporting for mysqli
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
// create mysqli object
$mysqli = new mysqli(/* fill in your connection info here */);

$email = $_POST['email']; // might want to validate and sanitize this first before passing to database...

// set query
$query = "SELECT COUNT(*) FROM users WHERE email = ?";

// prepare the query, bind the variable and execute
$stmt = $mysqli->prepare($query);
$stmt->bind_param('s', $email);
$stmt->execute();

// grab the result
$stmt->bind_result($numRows);
$stmt->fetch();

if ($numRows) {
    echo "<p class='red'>Email is already registered with us</p>";
} else {
    // ....
}

此链接也可能对您有所帮助:
http://www.php.net/manual/en/mysqli.quickstart.prepared-statements.php