與COUNT（..）不起作用的簡單預處理語句

Question

我收到以下預編譯語句代碼的錯誤。想知道是什麼原因，因爲它看起來都是正確的。

Notice: Connection failed: Prepared statement invalid: Operand should contain 1 column(s) in C:\xampp\htdocs\index.php on line 58 

下面的代碼：

$conn = new mysqli('localhost', 'root', '', 'myusers'); // this is confirmed to work for connecting 
// Check connection 
if ($conn->connect_error) { 
    trigger_error('Connection failed: ' . $conn->connect_error); 
    die(); 
} 
$stmt = $conn->prepare('SELECT COUNT(id) as count_u FROM Users WHERE (title=?, forename=?, surname=?)'); 
if (!$stmt) { // here, $stmt is false or such. 
    trigger_error('Connection failed: Prepared statement invalid: ' . htmlspecialchars($conn->error)); 
    die(); 
} 

Answer 1

使用

WHERE title=? 
    AND forename=? 
    AND surname=? 

Answer 2

使用和/或在您where子句

$stmt = $conn->prepare('SELECT COUNT(id) as count_u FROM Users WHERE title=? and/or forename=? and/or surname=?)'); 
$stmt->bind_param("sss", $title, $forename, $surname);