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)

Foreign Key Constraints

Let's look at this in the context of a primary key. When this primary key is referenced by a column in another table, this primary key becomes the foreign key of the other table. For example, consider the previously created database PACKT_ONLINE_SHOP:

DROP DATABASE IF EXISTS PACKT_ONLINE_SHOP;
CREATE DATABASE IF NOT EXISTS PACKT_ONLINE_SHOP;
USE PACKT_ONLINE_SHOP;
CREATE TABLE Customers
(
    CustomerID INT NOT NULL AUTO_INCREMENT,
    FirstName CHAR(50) NOT NULL,
    LastName CHAR(50) NOT NULL,
    Address CHAR(250) NULL,
    Email CHAR(200) NULL,
    Phone CHAR(50) NULL,
    Notes VARCHAR(750) NULL,
    BalanceNotes VARCHAR(750) NULL,
    PRIMARY KEY (CustomerID)
);
CREATE TABLE Orders
(
    OrderID INT NOT NULL AUTO_INCREMENT,
    ...