SQL is the language to use for communicating with databases. SQL stands for Structured Query Language and is pronounced like 'sequel.'
Almost all web and mobile apps store information in a database. For example, Everpath stores information about each of our courses in a database, and this information is easily accessible through our course pages.
But sometimes business users want to directly access the information. For example, let's say I want to know how many free courses are in our catalog. In this case, I'll need to query the database directly using SQL.
What is SQL?
(Note: this is written from the perspective of a business user, not as a developer or database administrator.)
Knowing SQL is a valuable skill for accessing and analyzing information that is stored in a database. There are several flavors of the SQL language depending on the database type, but the variations are relatively minor. SQL can be used to query data in places like Microsoft Access, MySQL, Microsoft SQL Server, Oracle SQL, and more.
Some of these databases have 'drag and drop' interfaces that can help you construct a SQL query. Still, it's helpful to understand SQL syntax so that you can modify queries as you wish.
To read data from a database, your SQL query will generally have the following three components:
- SELECT (the columns of data that you want returned)
- FROM (the tables that you want to access)
- WHERE (the conditions to filter your results)
Although there are many more components that can be added, queries for reading data will generally follow the SELECT, FROM, WHERE format. (Queries for updating, inserting, or deleting data have different formats that aren't covered here.)
If I wanted to list the free courses in the Everpath catalog, I'd use the following query:
- SELECT title
- FROM courses
- WHERE price = 'Free';
Getting started with SQL
Here are our recommendations for SQL tutorials:
- SQL Essential Training. This 2.5 hour video course from Lynda.com is a great general introduction for beginners. A subscription to Lynda.com costs $25 per month, but they do have a 7 day free trial and may also be available for free at your public library.
- Practical SQL Skills from Beginner to Intermediate. Udemy's $39 beginner course is also just over 2 hours and is highly rated by people who have taken it.
- Database Foundations. Compared to the two options above, Treehouse's course is slightly more geared towards developers. A subscription to Treehouse costs $25 per month.