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

我们可以使用 * 号来读取所有数据表中的字段：SELECT * FROM table_name

如需学习更多关于 SQL 的知识，请访问我们的 SQL 教程。

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)

$servername = "localhost";

$username = "username";

$password = "password";

$dbname = "myDB";

// 创建连接

$conn = mysqli_connect($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";

}

mysqli_close(%conn);

?>

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)

echo "

echo "

IdFirstnameLastnameEmailReg date";

class TableRows extends RecursiveIteratorIterator {

function __construct($it) {

parent::__construct($it, self::LEAVES_ONLY);

}

function current() {

return "

" . parent::current(). "";

}

function beginChildren() {

echo "

";

}

function endChildren() {

echo "

" . "\n";

}

}

$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 "

";

?>