mysql 與 mysqli 差異比較與用法完整指南

核心差異

mysqli 程式式用法

$conn = mysqli_connect('localhost', 'root', '123', 'db_test') or die('error');
$sql = \"SELECT * FROM db_table\";
$query = mysqli_query($conn, $sql);
while ($row = mysqli_fetch_array($query)) {
    echo $row['title'];
}

mysqli 物件導向用法

$conn = new mysqli('localhost', 'root', '123', 'db_test');
$sql = \"SELECT * FROM db_table\";
$query = $conn->query($sql);
while ($row = $query->fetch_array()) {
    echo $row['title'];
}

交易處理範例

$mysqli = new mysqli('localhost', 'root', '', 'DB_Lib2Test');
$mysqli->autocommit(false); // 開始交易
$mysqli->query($sql1);
$mysqli->query($sql2);
if (!$mysqli->errno) {
    $mysqli->commit();
    echo 'ok';
} else {
    echo 'err';
    $mysqli->rollback();
}

mysql_pconnect 補充說明

mysql_pconnect 建立持久連線，進程結束不釋放，類似連線池。優點：省去重複連線開銷；缺點：佔用記憶體與連線數，高併發易觸發 max_connections 限制。建議視流量決定是否使用。