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Which points to the blame for SQL not implementing Codd’s ideas right not lying at the feet of Codd’s being insufficiently precise, as claimed in the linked pap
by jameshart 4y ago
Which points to the blame for SQL not implementing Codd’s ideas right not lying at the feet of Codd’s being insufficiently precise, as claimed in the linked paper, but rather as a deliberate choice to simplify the relational model.
- kragen 4y agoi would rather say to make the relational model more complex
- goto11 4y agoSQL tables are multisets (sets allowing duplicates) rather than sets as defined by the relational model. This was likely a deliberate decision in order to make implementations simpler and faster, since it avoids some uniqueness checks. For example it is much simpler to implement UNION if you don't have to check for duplicates. But arguably this push some complexity to the user, since duplicates lead to all kinds of problems. On the other hand three-valued logic is obviously more complex than regular boolean logic. But I don't agree with the author that three-valued is in conflict with the relational model.