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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
[](https://liberapay.com/ltworf/donate)
Official website
================
More documentation can be found here https://ltworf.codeberg.pages/relational/
Install
=======
* Windows:https://ltworf.codeberg.pages/relational/download.html?exe
* Debian based: `apt-get install relational`
* Everyone else: Download the sourceshttps://ltworf.codeberg.pages/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.codeberg.pages/relational/allowed_expressions.html
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