A committed version of a data table is stored in a base table that includes a timestamp column that indicates when the most recent change to each row was committed. Changes to the base table are stored in three versioned tables: a version add table, a version modify table, and a version delete table. A version view table reconstructs the data stored in the base table and the versioned tables to provide an external view of each version. When a change is made, the change is stored in the appropriate versioned table with the corresponding timestamp from the base table. When the change is submitted, the "stored" timestamp in the versioned table is compared with the "current" timestamp in the base table. If the stored timestamp is equal to the current timestamp, then there is no conflict and the change is committed. If the stored timestamp is not equal to the current timestamp, then there is a conflict. A user may choose to merge and commit a conflict or to rollback and not commit the conflicting.