PHP MYSQL 使用 PDO 连接数据库并执行 SQL 语句

<?php
//获取GET信息
$driver_phone = $_GET["driver_phone"];
$route_from = $_GET["start_place"];
$route_to = $_GET["arrive_place"];
$start_time = $_GET["start_time"];
$arrive_time = $_GET["arrive_time"];
//创建PDO对象
$dsn = "mysql:host=??????;dbname=??????";
$db = new PDO($dsn, "??????", "??????");

//查询是否有重复数据
$sql = "select count(*) from carrides where driver_phone="$driver_phone"";
$result = $db->query($sql);
$rows = $result->fetch();
$rowCount = $rows[0];
//如果有重复数据
if($rowCount>=1){
    $sql = "update carrides set route_from="$route_from",route_to="$route_to",start_time="$start_time",arrive_time="$arrive_time" where driver_phone="$driver_phone"";	
} else {
    $sql = "insert into carrides (driver_phone,route_from,route_to,start_time,arrive_time) values ("$driver_phone","$route_from","$route_to","$start_time","$arrive_time")";	
}
$db->query("set names utf8");
$db->query($sql);
$db = null;
?>