Creating, Altering, and Dropping Tables

Imagine our OnlineStore is expanding rapidly! We started by tracking products, customers, and orders. But now, to manage our growing team, we need a dedicated place to store employee information, their names, roles, hire dates, and perhaps their department. How do we build this new structure within our existing database? And what if we later realize we forgot to include their department, or their job titles need more space, or perhaps a table is no longer needed? This is where managing table structures – creating, altering, and dropping them – becomes essential. These operations are fundamental to adapting our database to evolving business needs.

By the end of this lesson, we will be able to:

• Understand the importance of tables as the primary data storage structures.

• Use the CREATE TABLE statement to define and build new tables with appropriate columns, data types, and constraints.

• Modify existing table structures using the ALTER TABLE statement, including adding, dropping, and modifying columns, as well as managing constraints.

• Remove tables from the database using the DROP TABLE statement and understand the consequences.

Let’s dive in and learn how to sculpt the very foundation of our database!

The building blocks: Understanding tables

Before we jump into creating tables, let’s quickly recap why they are so crucial. In a relational database like MySQL, tables are the primary objects used to store data. Each table organizes data into rows (records) and columns (fields), representing a specific entity, like Products or Customers. Without well-defined tables, storing, managing, and retrieving information efficiently would be impossible. They provide structure and meaning to the raw data.

Creating new tables with CREATE TABLE

Whenever we need to store a new category of information in our database, we need a new table. For instance, if our OnlineStore decides to start tracking employee details or supplier information, we would create new tables specifically for Employees or Suppliers. The CREATE TABLE statement is our tool for defining the blueprint of these new tables – specifying what columns they will have, what type of data each column will hold, and any rules (constraints) that data must follow.

The CREATE TABLE statement is a Data Definition Language (DDL) command used to construct a new table in the database. When we create a table, we define:

1. Table name: A unique name for the table within the database (e.g., Employees).

2. Columns: Each column has a name (e.g., FirstName, HireDate) and a data type. ...