On 09/15/2017 03:10 PM, Dennis Lee Bieber wrote: > "single table" so no join logic needed. And I suspect the relational > algebra "project" would be considered the same as SQL "select" by most > folks <G>
As Stefan has said, it's sometimes useful to join a table with itself, though I have never done that myself. As for select and project, both are distinct operations and both required. In fact both operations are a part of the SQL "SELECT" command. The first bit, the list of fields, is the project part, and the "WHERE" part is the select part, as well as the join part. Guess SQL blurs the lines between the operations. And my point was if he needs those things then he's already reinvented the SQL SELECT, so he may as well just use SQL. Alternatively, use a LINQ-like library that implements the relational algebra for him. Sorry I was unclear. -- https://mail.python.org/mailman/listinfo/python-list
