要查询数据库并显示内容，可以使用PHP中的MySQLi扩展或PDO扩展。以下是一个简单的示例：

使用MySQLi扩展：

<?php$servername = "localhost";$username = "username";$password = "password";$dbname = "database";// 创建连接$conn = new mysqli($servername, $username, $password, $dbname);// 检查连接是否成功if ($conn->connect_error) {die("连接失败: " . $conn->connect_error);}// 查询数据$sql = "SELECT id, name, email FROM users";$result = $conn->query($sql);if ($result->num_rows > 0) {// 输出数据while($row = $result->fetch_assoc()) {echo "id: " . $row["id"]. " - Name: " . $row["name"]. " - Email: " . $row["email"]. "<br>";}} else {echo "0 结果";}$conn->close();?>

使用PDO扩展：

<?php$servername = "localhost";$username = "username";$password = "password";$dbname = "database";try {$conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);$stmt = $conn->prepare("SELECT id, name, email FROM users");$stmt->execute();// 设置结果集为关联数组$result = $stmt->setFetchMode(PDO::FETCH_ASSOC);foreach($stmt->fetchAll() as $row) {echo "id: " . $row["id"]. " - Name: " . $row["name"]. " - Email: " . $row["email"]. "<br>";}} catch(PDOException $e) {echo "Error: " . $e->getMessage();}$conn = null;?>

无论使用MySQLi扩展还是PDO扩展，都需要替换示例中的主机名、用户名、密码和数据库名以及查询的数据表和字段名称。