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@ -1,6 +1,11 @@
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Relational
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==========
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Relational an educational tool to provide a workspace for experimenting with *relational* *algebra*, an offshoot of first-order logic.
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It works on GNU/Linux, Windows and OS X.
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I test it on GNU/Linux and Windows. It probably works on other systems too.
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It provides:
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* A GUI that can be used for executing relational queries
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@ -11,39 +16,21 @@ It provides:
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Official website
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================
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More documentation can be found here http://ltworf.github.io/relational/
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More documentation can be found here https://ltworf.github.io/relational/
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Install
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=======
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Binary download for Windows can be obtained from the website.
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For Linux, check your distribution's packages, relational is available on Debian and Ubuntu.
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Syntax
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======
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These are some valid queries
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```
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σage > 25 and rank == weight(A)
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σ (name.upper().startswith('J') and age>21 )(people)
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Q ⋈ π a,b(A) ⋈ B
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ρid➡i,name➡n(A) - π a,b(π a,b(A)) ∩ σage > 25 or rank = weight(A)
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π a,b(π a,b(A))
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ρ id➡i,name➡n(π a,b(A))
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A ⋈ B
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```
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* Windows: https://ltworf.github.io/relational/download.html?exe
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* Debian based: `apt-get install relational`
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* Everyone else: Download the sources https://ltworf.github.io/relational/download.html?tar.gz
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Run from sources
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================
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If it needs some dependencies:
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* Qt5
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* Python 3.4 or greater
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* PyQt5
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* pyuic5 and pyrcc5
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For the dependencies, check `debian/control` for the build dependencies.
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You will need to run
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```
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@ -56,3 +43,26 @@ To launch the application, run
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```
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./relational.py
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```
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Syntax
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======
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These are some valid queries (using the provided example dataset)
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```
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# Join people and skills
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people ⋈ skills
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# Select people within a certain age range
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σ age > 25 and age < 50 (people)
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# Selection with complicated expression requires an extra set of () around the expression
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σ (name.upper().startswith('J') and age > 21) (people)
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# Cartesian product of people with itself, including only name and id
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ρ id➡i, name➡n (people) * π name, id (people)
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```
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For the selection, python expressions are used.
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The syntax is explained here: https://ltworf.github.io/relational/allowed_expressions.html
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Salvo 'LtWorf' Tomaselli