19cff69718
During a selection operation, each value is matched against a regular expression and then casting might be performed, depending on the results. This commit caches the result of the match so that a value is not matched multiple times in its lifetime.
Relational an educational tool to provide a workspace for experimenting with relational algebra, an offshoot of first-order logic.
It provides GUI that can be used for executing relational queries, and also provides a command line interface.
Provides a standalone Python module that can be used for executing relational queries, parsing relational expressions and optimizing them.
Official website
More documentation can be found here http://ltworf.github.io/relational/
Install
Binary download for Windows can be obtained from the website.
For Linux, check your distribution's packages, relational is available on Debian and Ubuntu.
Syntax
These are some valid queries
σage > 25 and rank == weight(A)
σ (name.upper().startswith('J') and age>21 )(people)
Q ⋈ π a,b(A) ⋈ B
ρid➡i,name➡n(A) - π a,b(π a,b(A)) ∩ σage > 25 or rank = weight(A)
π a,b(π a,b(A))
ρid➡i,name➡n(π a,b(A))
A ⋈ B
Run from sources
To launch the application, run
./relational_gui.py
If it needs some dependencies: Qt5, Python 3.4 or greater, PyQt5
It can run on osx but bugreports about that will be rejected.