| Author: | Gabriel Acosta |
|---|
Ï€real 
Pireal is a tool to evaluate and display the results of queries written in the language of relational algebra.
Platforms
- GNU/Linux
- Windows
- Mac OS X
Running
Running from sources
Requirements
Clone the repository:
git clone https://github.com/centaurialpha/pireal.git
or download the .zip file and running:
cd pireal python pireal.py
Syntax
- Semicolon at the end of each line is not necessary
- SQL style comments
-- This is a comment on Pireal
-- Other comment- Valid queries
q1 = people njoin skills q2 = select age > 25 (q1) q3 = project id, name, skill (q2)
or
project id, name, skill (select age > 25 (people njoin skills))
Implemented Operators
The operations are implemented in relation.py.
| Operator | Supported |
|---|---|
| Selection | Yes |
| Projection | Yes |
| Rename | No |
| Product | Yes |
| Union | Yes |
| Difference | Yes |
| Natural Join | Yes |
| Left Outer Join | No |
| Right Outer Join | No |
| Full Outer Join | No |
| Intersection | Yes |
| Division | No |
Tutorial
How to create a database
The database files have the extension .pdb (Pireal DataBase).
Syntax
- The name of the database is the name of
.pdbfile. - To define a table, in the first row must place the name followed fields, like this:
@relation_name:field1,field2. - The tuples separated by commas.
Example of a database.pdb file:
@people:id,name,age 001,Mike,15 002,Gabriel,24 003,Linus,45 @skills:id,skill 002,Python 003,Linux
How to create a table/relation
The table files have the extension .prf.
Syntax
- In
CSV (comma-separated-values)format. - The first row corresponds to the fields.
There are two ways to create a relationship or table:
- From the menu:
Relation/New Relation. - Or creating a file.
Example:
skills.prf
id,skill 23,Linux 7,GNU 6,Gamer 1,Python 9,Chef
Now you can load the relation from the menu Relation/Load Relation.
Video
