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Relational

Relational an educational tool to provide a workspace for experimenting with relational algebra, an offshoot of first-order logic.

I test it on GNU/Linux and Windows. It probably works on other systems too.

It provides:

A GUI that can be used for executing relational queries
A standalone Python module that can be used for executing relational queries, parsing relational expressions and optimizing them
A command line interface

Official website

More documentation can be found here https://ltworf.github.io/relational/

Install

Windows: https://ltworf.github.io/relational/download.html?exe
Debian based: apt-get install relational
Everyone else: Download the sources https://ltworf.github.io/relational/download.html?tar.gz

Run from sources

For the dependencies, check debian/control for the build dependencies.

You will need to run

make

to generate some .py files.

To launch the application, run

./relational.py

Syntax

These are some valid queries (using the provided example dataset)

# Join people and skills
people ⋈ skills

# Select people within a certain age range
σ age > 25 and age < 50 (people)

# Selection with complicated expression requires an extra set of () around the expression
σ (name.upper().startswith('J') and age > 21) (people)

# Cartesian product of people with itself, including only name and id
ρ id➡i, name➡n (people) * π name, id (people)

For the selection, python expressions are used.

The syntax is explained here: https://ltworf.github.io/relational/allowed_expressions.html