This site runs best with JavaScript enabled.Lesson 1: What is SQL?

Lesson 1: What is SQL?


So what the hell is SQL?

Hopefully youve heard of it in some shape or form or else you wouldnt be here. But lets clear up one of the most common (and community dividing) misconceptions first.

As far as Im concerned, its pronounced Sequel. There will be many amongst the data analyst community who think that it should be pronounced one letter at a time (ESS QUEUE ELLE).

Let's ask the expert.

SQL was developed by Donald Chamberlin and Raymond Boyce at IBM in the 1970s. Patrick Gillespie saved us a lot of time back in 2012 by having the great idea of emailing Don Chamberlin and just asking him outright which was correct. He created the language. We can only assume his would be the most definitive answer on the subject.

Patrick quotes the response he got in his article, Pronouncing SQL S Q L or Sequel:

Hi Pat,

Since the language was originally named SEQUEL, many people continued to pronounce the name that way after it was shortened to SQL. Both pronunciations are widely used and recognized. As to which is more “official”, I guess the authority would be the ISO Standard, which is spelled (and presumably pronounced) S-Q-L.

Thanks for your interest, Don Chamberlin

Don is clearly a gentleman in suggesting that the ISO Standard way is now more authoritative. But seeing as he sticks with his own original pronunciation himself, Im going to go with that too.

Weve started off on the right foot and got the most important issue out of the way early. So lets get into the bones of it.

If thats how we say it, what exactly is it?

SQL stands for Structured Query Language.

It lets us take things out of relational database systems, put new rows of data into them, amend records that are in there and remove records we dont need any more.

It was recognised as the standard language for relational databases by the American National Standards Institute way back in 1986.

If its a standard, does that mean I only have to learn it once and can use it everywhere?

No, of course not. If things were that simple I wouldnt need to write this series to get aspiring analysts over the first SQL hurdle.

All of the main relational database management systems use a form of SQL. They mainly have some variations in syntax and functionality as you delve deeper into them though.

Some of the most used RDMSes have their own flavours of SQL but learning the standard basics will give you a great start. Then you can use what you know to pick up the nuances of Microsoft SQL Server, PostgreSQL, MySQL, Oracle, DB2, SQLite and many more SQL dialects at your leisure.

It's still sounding a bit boring mate.

If some heads hit the desk there at the mention of syntax and RDBMSes please take a second to freshen yourselves up. I want to make the point that learning SQL doesnt have to be boring.

Its not exactly touring with Led Zeppelin in the 1970s exciting either. But it doesnt have to be the dry, dusty insomnia cure most places make it. Not by a long chalk.

In this SQL crash course, we are going to look at many areas of SQL.

This will include the main SQL commands such as SELECT, UPDATE, INSERT INTO and DELETE. Well look at functions such as SUM, COUNT and AVG. Well delve into joining tables using JOINS such as INNER JOIN, LEFT and RIGHT JOIN, OUTER JOIN and CROSS JOIN.

Added together, this knowledge will give you a major head-start on your way to becoming a SQL Grand Master.

Buckle up, its going to be a wild ride.

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