Going through a data schema and its types
An SQL database—structured and relational—is often made up of more than one table. In fact, more complicated databases may have dozens or even hundreds of tables. Every table should have a key. A key is a variable that is shared with another table so that the tables can be joined together. We will discuss specifics on joins later in this book. In this way, all the tables can be connected to one another, even if it would take several joins to do it. As you can imagine, these databases can be confusing, inefficient, and impractical. To make databases cleaner and easier to use, how tables are organized and interact with each other often follows a few common patterns. These patterns are called data schemas. There are several different popular schemas, and each meets specific needs, but this exam only covers two of the most basic schemas:
- Star
- Snowflake
The schemas are named after the shapes the tables make when...