Add project all columns (π *) to relational and multiset algebra

[rlaiola]

Reference issue

None.

What does this implement/fix?

This PR aims at providing a more flexible way to write queries based on the SQL standard and RDBMS implementations such as MySQL, PostgreSQL and MS SQL Server. In summary, it is possible to project all columns using the asterisk (*).

Note: To run the tests refer to http://dbis-uibk.github.io/relax/calc/local/uibk/local/0

Test 1: project all columns

π * (R)

or

pi * (R)

• Before:

• After:

How to test this PR?

Test it live at https://rlaiola.github.io/relax/calc/local/uibk/local/0. For automated tests visit https://rlaiola.github.io/relax/test.html

References

• https://www.w3schools.com/sql/sql_select.asp

[rlaiola]

PR https://github.com/dbis-uibk/relax/pull/215 must be merged before.