Big Data and AI

  Designing a robust database schema is crucial for data integrity, performance, and long‐term maintainability. In this module, we’ll cover: Creating and altering tables Defining keys and leveraging indexes By the end, you’ll know how to structure your data model to support reliable applications and fast queries. Creating and Altering Tables A well‐designed table lays the foundation of your database. Start by defining clear columns, appropriate data types, and necessary constraints. 1. CREATE TABLE Syntax sql CREATE TABLE employees ( employee_id SERIAL PRIMARY KEY, first_name VARCHAR(50) NOT NULL, last_name VARCHAR(50) NOT NULL, hire_date DATE NOT NULL, email VARCHAR(100) UNIQUE, salary NUMERIC(10, 2) CHECK (salary > 0) ); Key takeaways: Use SERIAL or IDENTITY for auto-incrementing primary keys. Choose string lengths ( VARCHAR ) based on real data. Apply NOT NULL to mandatory columns. Enforce business rules with CHECK constraints. 2. A...