如何使用php PDO查找和替换

我需要使用PHP7，有人建议我使用PDO。我的原始代码如下所示

 <?php 

function sentence()  {
    global $post;
mysql_connect("localhost", "user", "password") or die(mysql_error());
mysql_select_db("database") or die(mysql_error());
mysql_query('set names "utf8"'); 
$query="SELECT name FROM seo ORDER BY RAND() LIMIT 10;";
$result=mysql_query($query);
$num=mysql_numrows($result);

//Begin find and replace
while($row = mysql_fetch_array($result))
{
//this is the string to look into
$myString = $row['name'];
//this is the thing to look for
$patterns = array();
$patterns[0] = '/1111/';
$patterns[1] = '/2222/';
$patterns[2] = '/3333/';
$patterns[3] = '/4444/';
$patterns[4] = '/5555/';
$patterns[5] = '/6666/';
$patterns[6] = '/1234/';
//this is what you replace it with
$result1 = $post->post_title; 
//this is the echo
echo preg_replace($patterns, $result1, $myString);

}
mysql_close();
}


?>

---

如果您想替换一行中的某个内容，可以使用
更新
queryOk cool。这里看起来像什么？我对编程非常陌生。奇怪的是，你问的代码与数据库无关，基本上保持不变，不管你使用的是什么数据库。这真的是你上面贴的代码吗？
<?php

$hostdb   = 'localhost';
$dbname   = 'database';
$username = 'user';
$password = 'password';
$table    = 'seo';

    $pdo = new PDO("mysql:host=$hostdb;dbname=$dbname", $username, $password);
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    $sql  = "SELECT name FROM $table ORDER BY RAND() LIMIT 2;";
    $stmt = $pdo->prepare($sql);
    $stmt->execute();

    $result = $stmt->fetchAll();

            //echo '<pre>';
            //print_r($result);
            //echo '</pre>';  

?>