php / mysql更新表并在未找到匹配项的地方插入新记录

Question

I want to update a table based on the values from another table. If no record exists, then insert as new record. This code updates correctly but does not insert where records do no exist.

$results_google = mysql_query("upadate google set                
    Description = '".mysql_real_escape_string(trim(addslashes(strip_tags($row_first['product_description']))))."',
    Manufacturer = '".$row_first['product_vendor']."',
    Price = '".$row_first['product_price']."',                
    Title ='".$row_first['product_title']."'
    WHERE product_id = '".mysql_real_escape_string($row_first['product_id'])."';");
if(!$results_google) {      
    $google = "insert into `google`(`product_id`,`id`,`Description`,`Link`,`Manufacturer`,`Title`,
        `Price`,`Shipping_Weight`,`Image_Link`,`Brand`,`inv_id`)
        VALUES (
        '".mysql_real_escape_string($row_first['product_id'])."',
        '".mysql_real_escape_string($row_first['product_id'])."',
        '".mysql_real_escape_string(trim(strip_tags(addslashes($row_first['product_description']))))."',
        '".mysql_real_escape_string($row_first['product_link'])."',
        '".mysql_real_escape_string($row_first['product_vendor'])."',
        '".mysql_real_escape_string($row_first['product_title'])."',
        '".mysql_real_escape_string($row_first['product_price'])."',                             
        '".mysql_real_escape_string($row_first['weight'])."',
        '".mysql_real_escape_string($row_first['image_link'])."',
        '".mysql_real_escape_string($row_first['product_vendor'])."',
        '$inventory_id')";
    mysql_query ($google) or die("google".mysql_error());
}

Answer 1

If you are asking how to insert a row or update it if it already exists, you need to look into ON DUPLICATE KEY UPDATE . ON DUPLICATE KEY UPDATE will only check UNIQUE indexes or primary keys, so make sure the fields that will differ to cause an additional row are marked as unique (or you can do a multi-column unique index).

Read the documentation for INSERT ... ON DUPLICATE KEY UPDATE .

Answer 2

Although @Konerak's comment is really the right way to go, in combination with prepared statements and knowing your data (casting to ints for ints, using string functions for strings, etc.), I will answer the question as to why your code is not working as expected.

You are using an update query with a WHERE statement. If no matching row is found, no row is updated but the query does not return false because mysql_query only returns false on error and not finding a row to update is not an error. So as long as your query is valid, your if statement will always be false.

Edit: As mentioned in the comment below, you can use mysql_affected_rows() to check if no row was updated:

if (mysql_affected_rows() == 0)
{
  // insert a record
}

but I would really recommend going the ON DUPLICATE KEY UPDATE and prepared statements way.