UpdateException example

  $spec = [
    'type' => 'varchar',
    'description' => "New Col",
    'length' => 20,
    'not null' => FALSE,
  ];
  $schema = Database::getConnection()->schema();
  $schema->addField('my_table', 'newcol', $spec);

  // Example of what to do if there is an error during your update.   if ($some_error_condition_met) {
    throw new UpdateException('Something went wrong; here is what you should do.');
  }

  // Example function body for a batch update. In this example, the values in   // a database field are updated.   if (!isset($sandbox['progress'])) {
    // This must be the first run. Initialize the sandbox.     $sandbox['progress'] = 0;
    $sandbox['current_pk'] = 0;
    $sandbox['max'] = Database::getConnection()->query('SELECT COUNT([my_primary_key]) FROM {my_table}')->fetchField();
  }