While XMod Pro doesn't require that you know SQL to build basic solutions, the more SQL you know the more powerful solutions you can build. With that goal in mind, we've created this beginner's guide to SQL for those of you who want to learn more. We'll dispense with the theory and advanced topics, focusing on the core, basic features of SQL that you should know to work effectively in XMod Pro.
What is SQL and How Do I Pronounce It?
Back in the days before Skynet became sentient and computers ruled the world, humans needed a way to talk to databases -- to ask them questions -- to "query" them for information. So, they created SQL, which stands for Structured Query Language. Essentially, it's a way you can talk to the database to retrieve data or add, update, and delete data.
Since we all tend to want different data or ask our questions in different ways, you'll find a lot of features and functions in SQL that help you do that. We won't go into the advanced uses of SQL in this article. Our goal is to give you a basic understanding of the language and how to use it for standard operations - without overloading you with theory, advanced topics, or minutia.
SQL, by the way, is pronounced in two equally valid ways: 1) As the individual letters: S-Q-L; 2) "see-kwul" like "Seagull" but replace the "g" sound with "kw".
Foundations
First, a smattering of vocabulary to make your learning easier...
- Database: This is the bucket into which all your data and functions go. DotNetNuke and most modules store their data in a single database, so there is no rule that says a database has to contain one type of data. We save that for the Table.
- Table: The common analogy for a Table is that of a filing cabinet (I think they still make those). Lets think of a doctor's office since they still tend to push a LOT of paper around. A doctor's office may have a filing cabinet (or a room) filled with patient charts - information related to the patient's care. That filing cabinet full of patient charts would be a Table.
- Record/Row: A table is made up of records. Others call them rows. The terms are interchangeable. In our doctor's office example, each of the patient charts would be a record or row in our database.
- Column/Field: A column is a field is a column. These terms are also often used interchangeably. Columns are pieces of data that make up each record. So, in our example, the patent chart would be the record and items on that chart like blood pressure, weight, height, last visit date, etc. would each be columns in that record.
We could cover a lot of other vocabulary, but I always hate it when I have to spend too much time in "foundations" and not enough time learning something meaningful. So, we'll cover additional vocabulary items as we encounter them.