如何將 php 查詢存儲在變量中？

Question

我想從我的數據庫中獲取一個對象並將該對象存儲在一個真實的$teacher ，然后在$data使用它：

$teacher = "SELECT CONCAT(teacher.firstname, ' ', teacher.lastname) AS Name 
            FROM teacher 
            LEFT JOIN class ON teacher.id = teacher_fk 
            WHERE class.id = 1";


$data = "<h3 class='kartenUntertitel2'>teacher: '.$teacher.'</h3>";

我在我的網站上得到以下結果：

<h3 class="kartenUntertitel2">teacher: SELECT CONCAT(teacher.firstname, ' ', teacher.lastname) AS Name FROM teacher LEFT JOIN class ON teacher.id = teacher_fk WHERE class.id = 1</h3>"

但我想要的是：

<h3 class="kartenUntertitel2">teacher: Peter Muster</h3>

Answer 1

MySQL 數據庫示例：

您首先必須使用mysqli_connect()建立到數據庫的連接。 然后您必須使用mysqli_query()執行查詢。 如果查詢返回結果，您可以將其添加到$data變量中。

在最后，你應該釋放與內存（即結果消耗） mysqli_free_result()和關閉與連接mysqli_close()

$data = "";
$con = mysqli_connect("localhost", "my_user", "my_password", "my_db");
$sql = "SELECT CONCAT(teacher.firstname, ' ', teacher.lastname) AS Name 
            FROM teacher 
            LEFT JOIN class ON teacher.id = teacher_fk 
            WHERE class.id = 1";

// Perform query
if ($result = mysqli_query($con, $sql)) {
  $data = "<h3 class='kartenUntertitel2'>teacher: " . $result . "</h3>";
  mysqli_free_result($result);
}

mysqli_close($con);