Migrate {users}.data into {users_data}.
function overlay_update_8000() {
$query = db_select('_d7_users_data', 'ud');
$query
->condition('name', 'overlay');
$query
->addField('ud', 'uid');
$query
->addExpression("'overlay'", 'module');
$query
->addExpression("'enabled'", 'name');
$query
->addField('ud', 'value', 'value');
$query
->addExpression(1, 'serialized');
db_insert('users_data')
->from($query)
->execute();
// Migrate 'overlay_message_dismissed'.
$query = db_select('_d7_users_data', 'ud');
$query
->condition('name', 'overlay_message_dismissed');
$query
->addField('ud', 'uid');
$query
->addExpression("'overlay'", 'module');
$query
->addExpression("'message_dismissed'", 'name');
$query
->addField('ud', 'value', 'value');
$query
->addExpression(1, 'serialized');
db_insert('users_data')
->from($query)
->execute();
db_delete('_d7_users_data')
->condition('name', array(
'overlay',
'overlay_message_dismissed',
))
->execute();
}