Coffing Data Warehousing Software

What is SQL?

Hi, it’s Tera Tom, here to ask the burning question, “What is SQL”? It’s a great question because there are two answers. There are even two ways to say it.

A Brief History of SQL

Many people pronounce the acronym, “See-Quill.” Others will go to the mat for sounding out the letters, “Ess Que El.” Whichever you prefer, it stands for Structured Query Language. There are also SQL databases, but this article is about the language.

SQL is hugely important because it’s everywhere. If you have a relational database, you can almost certainly run SQL queries on it. The American National Standards Institute (ANSI) recognizes SQL as the standard language for relational database systems.

Which databases use SQL? Oracle, Sybase, Microsoft SQL Server, Access, Ingres, and more.

Let’s back up. Almost 70 years ago, a computer scientist for IBM San Jose Research Laboratory believed that he could improve upon the current standard of CODASYL databases. E. F. “Ted” Codd worked on his concepts through the 1960s and published them in 1970. Although Codd was part of the IBM team, they were slow to develop his relational database ideas. IBM enjoyed a solid revenue stream from CODASYL

IBM’s casual treatment of relational databases allowed Oracle to leap-frog them. Larry Ellison of Oracle studied IBM’s prelaunch publications and included Sequel in an Oracle Database – before an IBM product could even come to market. To avoid a big, nasty, international trademark fight, they changed the name to SQL.

Fast forward to today, when most databases use SQL, even if they also use proprietary extensions of their own. The fact is, you can use standard SQL commands to accomplish most of what you need to do on a database.

To recap: SQL is everywhere and it can do basically anything you need to do on a database. That’s why you should learn it and employers support it.

Learn More: Let’s Learn SQL! Lesson 1: Introducing SQL

Learning SQL

My online course begins with the most basic, common, and useful SQL commands. You’ll see the power that has made SQL ubiquitous.

The basic commands of SELECT, INSERT, UPDATE, DELETE, CREATE, and DROP will accomplish just about everything you need to do on a day-to-day basis. Let’s take a look at using SELECT to run a report. You can list all the information for every student in your student table by entering:

SELECT * 

FROM    Student_Table ;

See that sweet report that’s printed out all information available? The asterisk (*) told SQL to print out every column in the table. If you only need part of the information, use SQL to say so. Enter the columns you need:

SELECT

  Student_ID

, LAST_Name

, Class_Code

, Grade_Pt 

FROM Student_table ;

Take a look at the code sample above. Here’s an example of the kind of pro tips I share with you in my online courses and books, like Teradata Architecture and SQL. Most people would put commas behind column names, as appropriate – and that would be fine. However, putting commas in front is a better, more professional practice. It makes troubleshooting any errors much easier.

It also makes errors less likely. Imagine you went with your first instinct, commas behind names. What happens if you delete or comment out the last line? The list ends in a comma. ERROR.

Student_ID,

LAST_Name,

Class_Code,

Grade_Pt 

That’s how easy it is to run a basic SQL report. But don’t stop there. SQL has other commands that you can add to jazz up your report. You can sort report information many ways, by any column you choose, ascending or descending. Maybe you want to sort by more than one column, let’s say list all the folks with the same last name together, sorted by first name within that grouping. It’s all straightforward.

That should give you an idea of how much you can easily accomplish when you combine SQL and Teradata. Many users in your system would be happy with just that. But if you’re willing to learn a little more, SQL offers much, much more. That’s why I have 131 easily-digestible lessons in my online Let’s Learn SQL course.

More advanced work includes how to JOIN tables, so you can report on more than one table in a single place. For example, you might want to see columns from both a customer table and an order table. Derived tables are another advanced feature, one I struggled with, but teach you in the simplest way possible. Dates and calendars are another topic area.

I’ll show you how to use SQL to maintain moving sums and moving averages, create and troubleshoot macros, and write queries and subqueries. Before you know it, you’ll be ready to face even subjects that sound dangerous – like volatile tables!  

Remember, I’m always happy to come meet with you, to teach to your particular questions and needs. Book me (TeraTom). My contact information is below! 

 

Tom Coffing

CEO, Coffing Data Warehousing

Direct: 513 300-0341

Email: Tom.Coffing@CoffingDW.com

Website: www.CoffingDW.com