5 ms·
Out of curiosity, why do you say that no mainstream examples are a good representation of the relational model?
by stepbeek 5y ago
Out of curiosity, why do you say that no mainstream examples are a good representation of the relational model?
- fipar 5y agoMostly because of SQL. Among other problems, it’s not set-oriented: there are duplicates in SQL, but neither in relational calculus, nor in algebra. Column order has meaning in SQL but not in the relational model (another consequence of SQL not being based on sets). Another deviation is that SQL does not support column-less tables. On a rich-enough database (e.g. PostgreSQL) you can implement them yourself[0], but then that’s yet another incompatible across databases (one may think support for the empty table, which can only be one, is only of theoretical interest, but considering the model is based on set theory, it’s like not having a standard representation for the empty set). [0]: https://blog.jooq.org/creating-tables-dum-and-dee-in-postgresql/ https://blog.jooq.org/creating-tables-dum-and-dee-in-postgre...