Insert a mysql table into another table with sub query

Question

I'm Importing a CSV with two columns into an existing table using PHP (I'm using Joomla/Virtuemart)

The columns in the existing table are id (user id) and product_id.

The columns from the CSV file are product_sku and username so I need to first join to the appropriate tables to match the id (user id) with the username, and proudct_sku to product_id. I also need to trim leading zeros off the username, and whitespace from the productsku which I've done using sql.

I created a temporary table containing the data in the CSV, then joined onto both tables. I've got the data I need back but now need to insert that data into the existing table. Ideally I'd like to do this with mySQL, is it possible to do this as a sub query?

Would there be a massive difference in speed?

function do_query($file)
{

   //  $sql = "LOAD DATA INFILE ".$file['tmp_name']." INTO TABLE FavouritesTmp FIELDS TERMINATED BY ','  LINES TERMINATED BY '\n' (data1, data2)";

   $sql = "CREATE TEMPORARY TABLE FavouritesTmp (
                productsku VARCHAR(50) NOT NULL, 
                user VARCHAR(50) NOT NULL
        )";
   $this->_db->setQuery($sql);
   $this->_db->query();
   $handle = fopen($file['tmp_name'], "r");
   do
   {
      if ($data[0])
      {
         $sql = "INSERT INTO `FavouritesTmp` (productsku, user) VALUES 
                    ( 
                        '" . $data[0] . "', 
                        '" . $data[1] . "'
                    ) 
                ";
         $this->_db->setQuery($sql);
         $this->_db->query();
      }
   }

   while ($data = fgetcsv($handle, 1000, ",", "'"));
   $sql = "SELECT TRIM(LEADING  '0' FROM user) AS username, 
        productsku AS productsku, 
        jos_users.id AS id, 
        jos_vm_product.product_id AS product_id 
        FROM FavouritesTmp 
        LEFT JOIN jos_users ON (  TRIM(LEADING  '0' FROM username ) = jos_users.username )
        LEFT JOIN jos_vm_product ON  TRIM(productsku) = jos_vm_product.product_sku";
   $this->_db->setQuery($sql);
   print_r($this->_db->loadAssocList());
}

Answer 1

You can just use insert . . . select insert . . . select insert . . . select syntax:

INSERT INTO ExistingTable(username, productsku, id, product_id)
    SELECT TRIM(LEADING  '0' FROM user) AS username, 
           productsku AS productsku, 
           jos_users.id AS id, 
           jos_vm_product.product_id AS product_id 
    FROM FavouritesTmp 
    LEFT JOIN jos_users ON (  TRIM(LEADING  '0' FROM username ) = jos_users.username )
    LEFT JOIN jos_vm_product ON  TRIM(productsku) = jos_vm_product.product_sku;