• Unit 5: Introduction to SQL

    Structure Query Language (SQL) is a communication programming language that has been around for decades. It is the standard language for relational database management systems. Organizations cannot have an effective data management program without SQL. Therefore, organizations seek to hire personnel who understand basic SQL concepts. This unit will cover SQL, which is a database query language used for storing and managing data in relational database management systems (RDBMS).

    Completing this unit should take you approximately 6 hours.

    • Upon successful completion of this unit, you will be able to:

      • describe SQL and summarize its basic operators;
      • use relational views to simplify database processing; and
      • use data definition language (DDL) commands to create tables.

    • 5.1: SQL

      The official SQL standard was adopted by the American National Standards Institute (ANSI) in 1986. Then, the International Organization for Standardization (ISO) adopted SQL IN 1987. SQL is a standardized programming language used to perform various operations that manage relational database management systems (RDBMS). For example, if you are asked to identify and calculate from a table of customers whose last name is "Jones", SQL is a programming language used to communicate this command or query to the database. 

      There are many advantages to learning SQL. SQL is a universal language and intersects almost every industry. SQL is open source and easier to learn compared to other programming languages. You can manage millions of rows of data using SQL. Remember, RDBMS are designed to store millions of rows of data, and SQL is the language that lets you manage enormous amounts of data.

      • SQL for Beginners Page

        Watch this tutorial about SQL. Pay attention and take notes on the introduction to SQL. Stop the video at 6:35. The remainder of this video describes the installation, configuration, and operation of MySQL. MySQL is an RDBMS that is in widespread use. MySQL is open source, meaning that it is free to download and use. We will cover the basics of MySQL in section 5.1.3, and we will come back and watch some more of this video. Despite the name, MySQL is a database system, not the SQL programming language.

      • More on SQL Book

        Read this chapter. Take notes and be able to provide details about SQL, data definition language (DDL), data manipulation language (DML), and Structured English Query Language (SEQUEL). 

        SQL is a universal and standard language that interfaces with relational databases. SQL is used to communicate, analyze, and provide results from the data fields stored in a relational database. This next section will cover user-defined SQL objects, also known as functions. Your ability to understand and specify functions reduces the chance of errors in your SQL programming code. Also, remember when we discussed SQL injection attacks while looking at database security? Poorly constructed SQL code is what makes these kinds of attacks possible.

      • 5.1.1: Functions

        Functions are codes used to execute a command in an SQL server. SQL servers support two types of functions. (1) User-defined functions: Codes created by the user, and (2) System-defined functions: System functions that are built into the database. 

        SQL servers use two types of user-defined functions. (1) Table Valued Functions: Functions created by the user. This is identified by the term "CREATE" in the code. (2) Scalar Valued Functions: This type of function returns a single value each time it is used. Comparatively, system-defined functions are used to insert records and are system-built functions. The key to remember is that functions can be designed by the user or prebuilt. 

        SQL functions are commonly used, stored, and reused throughout SQL database applications. All SQL database applications use these functions for processing and/or manipulating data.

        • Practical SQL Functions Page

          Watch this video on SQL functions and how they are used in queries. Pay attention to the most commonly used functions in SQL. Take notes and learn the purpose of these common functions.

      • 5.1.2: Queries

        A query is a question or inquiry to a set of data within a database, commonly referred to as a database query. SQL queries require a "SELECT" statement which informs the system to start looking for specific data. Therefore, SQL query statements retrieve records asked from a database table. The "SELECT" statement is probably the most commonly used SQL statement employed by end users of database systems and is worthy of your careful attention. SQL is an industry-standard language that consists of user-defined and system-defined functions and queries.

        • Data Manipulation Language Book

          Read this chapter and take notes on the purpose and use of the clause SELECT and how the INSERT and DELETE statements are used to make changes to data. Also, note how functions are used in these statements.

        • Aggregate Functions and Views in SQL Page

          Watch this video on aggregate functions and views in SQL. Pay attention to the summary of the SQL Queries slide. Take notes on the definition and explanation of summary commands for information. For example, COUNT, SUM, MAX, MIN, and AVG. How does understanding SQL programming language help you manage millions of rows of data?

      • 5.1.3: MySQL

        First, MySQL and SQL are not the same. MySQL is one of the most used and popular RDBMS software in business. MySQL is second only to Oracle Database. Why is MySQL so important? It is easy to use, provides high performance, is an industry standard, and promotes data security. 

        • Essential MySQL Features Book

          Read this article on MySQL features you need to know. Pay attention and list the reasons that explain why MySQL is important. How does MySQL provide high performance and data security? 

        • Reporting and Analysis in SQL Page

          Now, go back to the tutorial you watched in Unit 5.1 on SQL. Watch this video from 1:54:00 to 2:41:00. Follow along with the tutorial, which explains MySQL functions and queries. 

      • 5.1.4: Clauses and Operators

        An SQL clause is a statement written as "GROUP BY". It is normally accompanied by aggregate functions like SUM. This provides a means of grouping the results of a dataset within certain database columns. So, a clause can be used with any SQL query to specify a condition. 

        SQL operators test a value against a Boolean value or expression. These values use operators such as AND, OR, XOR, and NOT. These statements compare values, and SQL will return a TRUE, FALSE, or UNKNOWN result.

        • Reporting and Analysis in SQL Page

          Watch this tutorial from 2:41:00 to the end.

          This unit described SQL and provided a summary of basic operators. SQL is a universal language that is used to manage and access an RDBMS. SQL can have user-defined and system-defined functions. SQL allows users to ask questions or conduct inquiries on data. This is done through the use of RDBMS software for SQL.

          MySQL is the RDBMS software learned in this unit. This is an open-source database system that is in wide use. Using the SQL language to communicate with a query in a database system is one way to reveal results. SQL can be used to reveal group results and Boolean values based on clauses and operators. Next, you will learn how to request organizational data from RDBMS operating on the internet.

    • Study Guide: Unit 5

      We recommend reviewing this Study Guide before taking the Unit 5 Assessment.

    • Unit 5 Assessment

      • Unit 5 Assessment Quiz
        Receive a grade

        Take this assessment to see how well you understood this unit.

        • This assessment does not count towards your grade. It is just for practice!
        • You will see the correct answers when you submit your answers. Use this to help you study for the final exam!
        • You can take this assessment as many times as you want, whenever you want.