/**
  * Creates an INSERT SQL-statement for $table with multiple rows. Drop in replacement for the same function from core database connections, because this does not allow NULL.
  *
  * @param string $table Table name
  * @param array $fields Field names
  * @param array $rows Table rows. Each row should be an array with field values mapping to $fields
  * @param boolean $no_quote_fields See fullQuoteArray()
  * @return string|NULL Full SQL query for INSERT, NULL if $rows is empty
  */
 protected function INSERTmultipleRows($table, array $fields, array $rows, $no_quote_fields = FALSE)
 {
     // Build query
     $query = 'INSERT INTO ' . $table . ' (' . implode(', ', $fields) . ') VALUES ';
     $rowSQL = array();
     foreach ($rows as $row) {
         // Quote and escape values
         $row = $this->db->fullQuoteArray($row, $table, $no_quote_fields, TRUE);
         $rowSQL[] = '(' . implode(', ', $row) . ')';
     }
     $query .= implode(', ', $rowSQL);
     return $query;
 }