php如何查詢數(shù)據(jù)庫并顯示內(nèi)容

要查詢數(shù)據(jù)庫并顯示內(nèi)容，可以使用PHP中的MySQLi擴展或PDO擴展。以下是一個簡單的示例：

使用MySQLi擴展：

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database";

// 創(chuàng)建連接
$conn = new mysqli($servername, $username, $password, $dbname);

// 檢查連接是否成功
if ($conn->connect_error) {
    die("連接失敗: " . $conn->connect_error);
}

// 查詢數(shù)據(jù)
$sql = "SELECT id, name, email FROM users";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // 輸出數(shù)據(jù)
    while($row = $result->fetch_assoc()) {
        echo "id: " . $row["id"]. " - Name: " . $row["name"]. " - Email: " . $row["email"]. "<br>";
    }
} else {
    echo "0 結(jié)果";
}

$conn->close();
?>

使用PDO擴展：

<?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();

    // 設(shè)置結(jié)果集為關(guān)聯(lián)數(shù)組
    $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;
?>

無論使用MySQLi擴展還是PDO擴展，都需要替換示例中的主機名、用戶名、密碼和數(shù)據(jù)庫名以及查詢的數(shù)據(jù)表和字段名稱。