Book Image

The SQL Workshop

By : Frank Solomon, Prashanth Jayaram, Awni Al Saqqa
Book Image

The SQL Workshop

By: Frank Solomon, Prashanth Jayaram, Awni Al Saqqa

Overview of this book

Many software applications are backed by powerful relational database systems, meaning that the skills to be able to maintain a SQL database and reliably retrieve data are in high demand. With its simple syntax and effective data manipulation capabilities, SQL enables you to manage relational databases with ease. The SQL Workshop will help you progress from basic to advanced-level SQL queries in order to create and manage databases successfully. This Workshop begins with an introduction to basic CRUD commands and gives you an overview of the different data types in SQL. You'll use commands for narrowing down the search results within a database and learn about data retrieval from single and multiple tables in a single query. As you advance, you'll use aggregate functions to perform calculations on a set of values, and implement process automation using stored procedures, functions, and triggers. Finally, you'll secure your database against potential threats and use access control to keep your data safe. Throughout this Workshop, you'll use your skills on a realistic database for an online shop, preparing you for solving data problems in the real world. By the end of this book, you'll have built the knowledge, skills and confidence to creatively solve real-world data problems with SQL.
Table of Contents (13 chapters)

First Normal Form (1NF)

What we saw in the solution for this situation is called the first normal form. Why? Because it adheres to the following four rules:

  • Every column must be single-valued
  • The data type of all the data in any column should be uniform
  • Every column should have a unique name
  • The order in which the records are ordered does not matter

As you can see, the column names in our tables are unique. Every column has only one data type (in our case, all the values are strings—even the employee IDs are strings). There are no multi-valued cells in the tables. The fourth one gives us the freedom to put the data in any order.

Remember the situation where Jon Doe owned 300 servers, and the server names were all jammed in a single cell? This is not allowed in the first normal form because it makes update operations difficult. The normal form helps prevent such situations.

Note

The first normal form is considered the least requirement for...