Among the things I'm sometimes asked by new webmasters are "What is MySQL?", "What is SQL" and "What is a database?". These questions arise because such terms tend to surface all over the place in connection with the creation of a website. This article explains them in (hopefully) plain English.
This article is written from the point of view of a webmaster and is directed at potential webmasters (or existing webmasters) who are suddenly confronted by cryptic terms like "MySQL database" or "PostgreSQL database" and the like.
It is not meant to be a rigorous academic definition for programming students. If you are one, you should consult a programming book for the proper definition. The explanation below is meant for the layperson who sees these terms pop up in places like web hosts' feature lists and the "System Requirements" lists for various web software like PHP scripts, and wonder what it means, and whether it's something that they need to be worried about. In other words, this guide is meant for a non-technical audience seeking to get the big picture and see if it is relevant to them.
(Note: if you're not sure what a web host is, you should read How to Make / Create Your Own Website: The Beginner's A-Z Guide for an explanation of this and other basic webmaster terms.)
Before I can answer what MySQL means, I have to explain what a computer "database" means.
Essentially, where computers are concerned, a database is a just collection of data. Specialised database software, like MySQL, are just programs that lets you store and retrieve that data as efficiently as possible.
A little analogy may help make it clearer why we use specialised database software. Think about the documents stored on your computer. If you were to save all your documents using a (brain-dead) file naming scheme like "1.doc", "2.doc", "3.doc", ... "9999999.doc" (etc), you will eventually face a problem of finding the right file if you're looking for a specific document. For example, if you're looking for a business proposal you made some time ago to XYZ Company, which file should you open? One way is to sequentially check every single file, starting from "1.doc", till you get the right data. But this is obviously a highly inefficient method of getting the right file. And it's primarily the result of a highly inefficient method of storing your data (ie, saving your files) in the first place.
Now, this is of course a ridiculous example. I mean, no one I know saves files with names like these, and even if so, there are many search software that can help you locate the correct file without your having to manually open every single one in sequence. But it serves to make the point that once you have a lot of data, if you don't have a good system of organising ("organizing" in American English) it, finding the correct piece of data is a very time consuming operation. And it becomes more time consuming as the amount of data grows.
A database software is a type of computer program that is designed to handle lots of data, but to store them in such a way that finding (and thus retrieving) any snippet of data is more efficient than it would have been if you simply dumped them willy nilly all over the place. With such database software, if you (say) keep a list of customers and their shipping addresses, entering and retrieving information about your one millionth customer will not take much longer (if at all) than entering and retrieving information about your 1st customer.
Database programs have many different methods for storing and retrieving data, as well as for organising the stored data on the computer. One popular way for accessing data, both to store and to retrieve it, is to use a computer language called "SQL" (often pronounced as "sequel"). SQL was specially designed for database access.
There are many databases that support the use of SQL to access their data, among them MySQL and PostgreSQL. In other words, MySQL is just a type of database, one of many. The same goes for PostgreSQL. These two databases are commonly used by programs that run on websites, which is why you often see one or both of them being advertised in the feature lists of web hosts, as well as being listed as one of the "system requirements" for certain web software (like blogging software or content management systems (CMS)).
For the average webmaster, one who is not writing computer programs for their websites, the pros and cons of MySQL versus PostgreSQL or some other database are not important. All you need to be concerned about is whether your web host provides the database software that your web application needs. Generally, if you use one of the popular blogging software or CMS software, this will often be MySQL. In fact, since practically every commercial web host provides MySQL as part of one or more of its hosting packages, chances are that you probably don't even have to worry about this.
As mentioned in the previous section, if you use a blogging or CMS software (like WordPress, Drupal or Expression Engine), you will need to place your website on a web host that provides you with a MySQL database. The database will be used by the software to store all your posts (articles), web pages and visitors' comments.
If, on the other hand, your website was created using a web editor like Dreamweaver or KompoZer, and you did not integrate a blog or some other web-based software into your site, chances are that you don't need MySQL. In any case, if you're not sure, you can always check the "system requirements" page for the software that you want to use to find out whether you'll need MySQL.
(Before you ask, the feedback form generated by the Feedback Form Script Wizard does not need MySQL. Not all web-based programs require a MySQL database; only those that need to store data.)
For the vast majority of webmasters, you don't need to learn SQL or learn how to use MySQL, even if you're setting up a blog. The software you use, be it WordPress or something else, will do all the dirty work of storing and retrieving your data for you. All you need to learn is how to use that particular software (eg, WordPress). Things like MySQL and other databases are like the engines of a car. Just as you don't need to learn how to design a car engine to be able to use a car, so also you do not need to know how to directly write to or read a MySQL database to use a blogging software.
Of course, if you are a programmer, intending to write a computer program that actually accesses MySQL or some other SQL database, then you will need to learn SQL (as well as a programming language). But then, if you are one, you probably already knew that. Note for the newcomer: you don't need to be a programmer to be a webmaster. Creating a website, even if you manually code your website directly in HTML, is not programming. So don't worry.
If you are reading this article to find out the meaning of these terms, chances are that you'll find the other articles listed below helpful in clarifying other terms frequently used in webmaster literature:
How to Make / Create Your Own Website: The Beginner's A-Z Guide — this is a step by step guide on how to design your own website. It is written for the newcomer and is thus written in plain English (rather than webmaster-speak). Read it if you don't already have a website; it will answer a lot of your other questions as well as explain many important terms that you'll find everywhere, including "web host", "domain name", etc.
What Does It Mean to Park a Domain Name? Domain Name Parking Explained — if you're puzzled by everyone talking about how you can park a domain name, read this article to find out more.
Should You Choose a Linux or a Windows Web Hosting Package? Is There Such a Thing as a Mac Web Host? — web hosts usually tell you whether they are running Linux, FreeBSD or Windows. What's that all about?
Glossary of Frequently Used Webmaster Terms — brief definitions of some terms can also be found on this page.
There are undoubtedly many other terms that you have encountered as you go about setting up a website. If it's a common query, chances are that I also have an article on it somewhere on thesitewizard.com. You can either search for these using my internal search engine, check out the index of topics and categories, or simply peruse the site map. Since it's possible that I've organised information differently from the way you mentally categorise things (and perhaps even use different terms or spelling), if you can't find what you want using one of the above methods, try another.
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