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)

UNION JOIN

The UNION operation is used to combine two queries. Let's look at the syntax:

SELECT [COLUMNS LIST] FROM [TABLE NAME]
UNION 
SELECT [COLUMNS LIST] FROM [TABLE NAME]

However, the most important point to remember when we use the UNION operation is to ensure the following:

  • Both query columns have similar data types
  • Both query columns are in the same order

Let's take a look at the following exercise to see how the UNION query functions.

Exercise 6.05: Implementing a UNION JOIN

The store manager wants a telephonic feedback survey from everyone who the store employees work with. This implies that there's a list of suppliers and customers and their full names, along with their contact numbers. To do this, perform the following steps:

  1. In a new query window, write the following query:
    SELECT CONCAT(Customers.FirstName,' ',Customers.LastName) as 'FULL NAME',
            Customers...