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The SQL Workshop

The SQL Workshop

By : Frank Solomon , Prashanth Jayaram , Awni Al Saqqa , Rakesh Kumar Pandey, Shubham Jain, Fiodar Sazanavets, Aaditya Pokkunuri, Shashikant Shakya, Dixit Patel , Pradeep Kumar Gupta, Scott Cosentino
4.8 (14)
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The SQL Workshop

The SQL Workshop

4.8 (14)
By: Frank Solomon , Prashanth Jayaram , Awni Al Saqqa , Rakesh Kumar Pandey, Shubham Jain, Fiodar Sazanavets, Aaditya Pokkunuri, Shashikant Shakya, Dixit Patel , Pradeep Kumar Gupta, Scott Cosentino

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)
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Checking for NULLS

Before we learn to handle NULL values, let's define a NULL value. NULL equals nothing in SQL, so a field that has no value is considered NULL. Usually, NULL fields are the result of having optional fields in your tables.

Checking NULL values can be done using the following two special keywords, as it cannot be done using the logical operators:

  • IS NULL
  • IS NOT NULL

    Note

    An important point to highlight is the fact that fields with a value of 0, or invisible characters such as spaces, are not considered NULL. NULL fields are fields that are left blank.

Exercise 5.06: Searching for NULL Values

Ideally, we want all customers' first names to be in our system. For any customer whose first name is missing from our data, we want to contact the customer and ask them about the missing information. To do this, we require a report of all the customers with missing first names:

  1. Retrieve the middle name, last name, and phone number columns...
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The SQL Workshop
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