SQL, as we have already established, is built on collections of tables. These tables can be linked together by queries to form increasingly complex tables, which allows us to draw conclusions that would otherwise be extraordinarily difficult to obtain.
There are some very powerful (yet weird) things we can do to create more useful queries.
It doesn't take very long to learn SQL, because it's a very simple scripting language with only four basic operations. No matter how complex you make your queries, with any number of conditions and tests, ultimately it boils down to CRUD. Why is it, then, that so few people can develop databases effectively?
So, we've looked at the four basic SQL commands, but we haven't really seen any useful examples of how they would work. In a moment, we'll look at a set of commands that will create a basic database, fill it with some values, and run a simple SELECT command.
These commands are designed to run
CRUD: Create, Read, Update, Destroy.
These are the four basic database operations. Logically, they're the four basic data operations as well.
CREATE - The act of producing new data which has not previously been introduced to the system. This data can be produced internally (through calculations, mostly) or externally (through input).
READ - The act of retrieving
In today's society, it's virtually impossible to find anyone who hasn't worked with Microsoft Excel at some point. We are somewhat familiar with the idea of spreadsheets and tables. We've written a simple macro or two. And, of course, there is great value to Excel and its competitors.
But Excel is weak. It's virtually impossible