Preparing SQL Statements with PDO

Question

My code looks like this:

// Connect to SQLite DB
DB(\'/path/to/sqlite.db\');

DB(\'BEGIN TRANSACTION;\');

// These loops are just examples.
for ($i = 1; $i          


        

Answer 1

Unfortunately I think that the problem may be with the structure of your code.

In your loop of INSERT statements, the statements are all identical and there is no need to call $db->prepare each time. The idea behind prepared statements is that you call $db->prepare() once, and execute() can be called multiple times on the same statement object. You're calling $db->prepare() every time, which is causing overhead in parsing the SQL statement and creating a new object.

Consider re-writing your DB() function like this:

function do_query($db, $pdo_statement, $query, $args)
{
    if ($pdo_statement->execute($args) === true)
    {
        if (stripos($query, 'INSERT') === 0)
        {
          return $db->lastInsertId();
        }
        if (stripos($query, 'SELECT') === 0)
        {
          return $result->fetchAll(PDO::FETCH_ASSOC);
        }
        return $result->rowCount();
    }
}

function DB($query)
{
    static $db = null;

    if (is_file($query) === true)
    {
      $db = new PDO('sqlite:' . $query, null, null, array(PDO::ATTR_ERRMODE => PDO::ERRMODE_WARNING));
    }

    else if (is_a($db, 'PDO') === true)
    {
      $result = $db->prepare($query);

      if (is_a($result, 'PDOStatement') === true)
      {
        $args = func_get_args();
        if (is_array($args[1])) {
            $ret = array();
            foreach ($args[1] as $args) {
                $ret[] = do_query($db, $query, $result, $args);
            }
            return $ret;
        }

        return do_query($db, $query, $result, array_slice(func_get_args(), 1));
      }

      return false;
    }

    return true;
}

So if you want to run the same query with lots of values, you create two-dimensional array of the values you want to insert, and call DB('INSERT INTO....', $values). The DB() function checks to see if the second parameter to the function (after $query) is an array and if so it loops through running $query against the values in the array. This way, the loop doesn't involve re-preparing the SQL statement each time, just re-executing it with different values. The return value of the function will be an array of the results of each query.