Migrate {users}.data into {users_data}.
function block_update_8005() {
$query = db_select('_d7_users_data', 'ud');
$query
->addField('ud', 'uid');
$query
->addExpression("'block'", 'module');
$query
->addExpression("'block'", 'name');
// Take over the extracted and serialized value in {_d7_users_data} as-is.
$query
->addField('ud', 'value');
$query
->addExpression('1', 'serialized');
$query
->condition('name', 'block');
db_insert('users_data')
->from($query)
->execute();
db_delete('_d7_users_data')
->condition('name', 'block')
->execute();
}