🧪 PeriodicBash (PostgreSQL + Bash CLI + Normalization)

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A Bash application to search for elements of the periodic table. The main objective was to normalize and correct errors in an already existing database periodic_table_old.sql to transform it into periodic_table.sql. Avoiding data redundancy (duplication), guaranteeing data atomicity (one field, one data point), and data integrity.

🚀 Key Features

• Dump of the original database (periodic_table_old): The database contains inconsistent data
  • Lowercase symbols: Like he and li, and the fictional element moTanium.
  • Lack of referential integrity: There is no FOREIGN KEY between properties and elements, allowing orphaned records.
  • Redundant constraints: Redundant UNIQUE constraints on primary keys.
  • Risk of incomplete data and inconsistent JOINs: melting_point and boiling_point in properties allow nulls, which can cause information loss or unexpected behavior when operating or filtering such data without a value.
  • Mandatory fields exposed in elements: symbol and name allow NULL, which would make it possible to register anonymous elements or elements without a symbol in the main catalog.
  • Repeated attributes and over-fragmentation: type should be an independent table (3NF) and the 1-to-1 division between elements and properties requires making unnecessary JOINs.
• Dump of the normalized database (periodic_table.sql): The new database corrects the errors of its predecessor periodic_table_old
  • Uppercase symbols: All chemical symbols have their first or only letter capitalized (e.g., He, Li).
  • Referential integrity: A FOREIGN KEY was added between properties and elements guaranteeing referential integrity, connecting tables and avoiding erroneous data.
  • No redundant constraints: If a constraint is not needed, it is not implemented, benefiting the maintenance of the database.
  • Impossibility of empty data: By design, empty data is no longer accepted in any field.
  • Normalization: The type field is separated from properties and replaced by a Foreign Key called type_id, which is related to type_id of the type table, complying with the Third Normal Form (3NF).
• element.sh script: A Bash Script that allows querying the information of a periodic table element registered in the database (periodic_table.sql).

📂 Project Structure

.
├── element.sh             # Main CLI executable script
├── periodic_table.sql     # Dump of the normalized database
├── periodic_table_old.sql # Dump of the original unnormalized database
└── README.md              # Project documentation

🛠️ Technologies Used

• Database: PostgreSQL
• Language: Bash / Shell Scripting (psql CLI)

💻 Installation and Execution

Prerequisites

Have PostgreSQL installed and configured in your local environment.

Steps

1. Clone the repository:

  git clone https://github.com/Aki-new/PeriodicBash.git
  cd PeriodicBash

2. Create and import the database schema:

  psql -U postgres < periodic_table.sql

Warning

Careful:
Make sure to execute psql -U postgres < periodic_table.sql and not psql -U postgres < periodic_table_old.sql, otherwise you will import the database without the fixes and normalizations I performed.

3. Give permissions to the application:

  chmod +x element.sh

👨‍💻 Usage Guide

• If you execute directly ./element.sh you will get a message saying Please provide an element as an argument.
• For it to run you must give it a parameter, it can be the atomic number, a chemical symbol or directly the name

    # Examples
    ./element.sh 1
    ./element.sh H
    ./element.sh Hydrogen

• Any sample input will generate the same output

    The element with atomic number 1 is Hydrogen (H). It's a nonmetal, with a mass of 1.008 amu. Hydrogen has a melting point of -259.1 celsius and a boiling point of -252.9 celsius.
  

📜 Credits and Acknowledgments

• Origin of the prompt / dataset: This project is one of the challenges required to obtain the Relational Database Certification from freeCodeCamp.
• Implementation: The bash script logic (element.sh) and the structuring of the PostgreSQL schema (periodic_table.sql) were completely developed as an individual solution to the proposed problem.