BS12's lasting contribution to history was the use of a new query language, based onISBL, created at their UK Scientific Centre. Details of the engine were picked up from the famous System R underway in the US at the same time, but they decided to dispose with SQL and modify ISBL instead.
BS12 included a number of interesting features that still have yet to appear on SQL-based systems, some a side effect of using ISBL, others due to deliberate design. For instance, a view could be based on a statement that was table-scope as opposed to column-scope. This allowed you to create views that represented a difference between two tables for instance.
Another feature that could have easily been included in SQL systems is the use of a system tables holding the structure of the database. New tables can be created by inserting a row into TABLES, and then rows added to it by inserting into COLUMNS. SQL systems have features to return similar data, but they aren't SQL based and therefore you can't do something as simple as SELECT * FROM TABLES WHERE size>10000, a particularly useful query.
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