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)

6. JOINS

Activity 6.01: Implementing JOINS

Solution:

  1. Look at the tables involved in obtaining and identifying the common columns. If you look closely at the following diagram, you will notice that the data that's required is scattered across not just two tables but three, that is, Orders, OrderItems, and Products.

    In cases like these, we'll have to perform multiple joins, with the first join being between the Orders and OrderItems table to get price details, and the second join being between the OrderItems and Products table to get the product information.

  2. In a new query window, implement this logic into the query:
    SELECT Orders.OrderNumber,
    OrderItems.UnitPrice,
    OrderItems.Quantity,
    Products.ProductName
    FROM Orders JOIN OrderItems ON Orders.OrderID =   OrderItems.OrderID 
         JOIN Products ON OrderItems.ProductID = Products.ProductID

    In this query, we joined the Orders and OrderItems tables using the OrderID and joined the Products and OrderItems tables using...