插入记录，避免在一个日期重复，并在下一个日期插入相同的记录

Question

我每天都有几个要插入Mysql数据库的项目。数据包含重复记录我只想插入不需要重复项目的不同记录。我已经这样做但是当我第二天运行代码时，它会用新的代码替换数据。我不想丢失以前的数据。我需要先前和新的数据，两天都没有重复数据。

有人这样工作吗？提前致谢

<?php
set_time_limit(0); 
$dbhost = "localhost";
$dbuser = "root";
$dbpass = "";
$dbname = "crawl";
$conn = mysql_connect($dbhost, $dbuser, $dbpass) or die ("Error connecting to database");
mysql_select_db($dbname, $conn);
$product_titles = array();
$q1 = mysql_query("SELECT * FROM `product-title`");

while($res1 = mysql_fetch_assoc($q1))
{
    $product_titles[] = $res1['title'];
}
$q2 = mysql_query("SELECT * FROM `product-list-url`");
while($res2 = mysql_fetch_assoc($q2))
{
    $url = $res2['url'];
    $html = file_get_contents($url);        
    $doc = new DOMDocument(); 
    @$doc->loadHTML($html);     
    $xpath = new DOMXPath($doc);
    foreach($product_titles as $product_title)
    {
        $found = $xpath->evaluate("boolean(//span[contains(text(), '$product_title')])");
        if($found == false)
        {
            //echo "Not Found";       
        }

        if($found == true)
        { 
            $elements = $xpath->evaluate("//span[contains(text(), '$product_title' )]/following-sibling::div/span[@class='list_sale_price']");
            if (!is_null($elements)) 
            {
                foreach ($elements as $element) 
                {
                    $nodes = $element->childNodes;
                    foreach ($nodes as $node) 
                    {
                        $price = $node->nodeValue;
                        $price1 = preg_replace('/[^0-9-.]/','',$price);
                        $date = date('y-m-d');
                        mysql_query("INSERT IGNORE INTO `prices` (`url`, `ptitle`, `price`, `date`) VALUES ('$url','$product_title', '$price1', '$date')") or die(mysql_error());         }
                   }
               }   
           }
       }
    }
}
?>