读取数据

PHP MySQL 读取数据

当 PHP 连接到 MySQL 数据库后，需要向数据库读取数据？那么怎么读取呢？一起来看看。

从 MySQL 数据库读取数据 SELECT 语句用于从数据表中读取数据:

```SELECT column_name(s) FROM table_name

如需学习更多关于 SQL 的知识，请访问我们的 SQL 教程。

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以下实例中我们从表 MyGuests 读取了 id, firstname 和 lastname 列的数据并显示在页面上：

实例 (MySQLi - 面向对象)
----

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

// 创建连接 $conn = new mysqli($servername, $username, $password, $dbname); // 检测连接 if ($conn->connect_error) { die("Connection failed: " . $conn->connect_error); }

$sql = "SELECT id, firstname, lastname FROM MyGuests"; $result = $conn->query($sql);

if ($result->num_rows > 0) { // 输出每行数据 while($row = $result->fetch_assoc()) { echo "
id: ". $row["id"]. " - Name: ". $row["firstname"]. " " . $row["lastname"]; } } else { echo "0 results"; } $conn->close(); ?>

以下实例读取了 MyGuests 表的所有记录并显示在 HTML 表格中：

实例 (PDO)
----

<?php echo "

class TableRows extends RecursiveIteratorIterator { function construct($it) { parent::construct($it, self::LEAVES_ONLY); }

function current() {
    return "<td style='width: 150px; border: 1px solid black;'>" . parent::current(). "</td>";
}

function beginChildren() {
    echo "<tr>";
}

function endChildren() {
    echo "</tr>" . "

"; } }

$servername = "localhost"; $username = "username"; $password = "password"; $dbname = "myDBPDO";

try { $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password); $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); $stmt = $conn->prepare("SELECT * FROM MyGuests"); $stmt->execute();

// 设置结果集为关联数组
$result = $stmt->setFetchMode(PDO::FETCH_ASSOC);

foreach(new TableRows(new RecursiveArrayIterator($stmt->fetchAll())) as $k=>$v) {
    echo $v;
}
$dsn = null;
}

catch(PDOException $e) { echo "Error: " . $e->getMessage(); } $conn = null; echo "