Implements hook_field_schema().
function datetime_field_schema($field) {
$db_columns = array();
$db_columns['value'] = array(
'description' => 'The date value',
'type' => 'varchar',
'length' => 20,
'not null' => FALSE,
);
$indexes = array(
'value' => array(
'value',
),
);
return array(
'columns' => $db_columns,
'indexes' => $indexes,
);
}