Relational Databases
We have been using the term relational quite a bit, it's time we actually go over what that means! A relational database is a type of database that stores data so that it can be easily related to other data. For example, a user can have many tweets. There's a relationship between a user and their tweet.
In a relational database:
- Data is typically represented in "tables".
- Each table has "columns" or "fields" that hold attributes related to the record.
- Each row or entry in the table is called a record.
- Typically, each record has a unique
Idcalled the primary key.
Example Relational Database
Here is an example of a small relational database. This database has 3 tables, Students, Courses, and StudentCourses. The StudentCourses table manages the relationship between the Students and the Courses tables.
Example 1: Sam
- Sam has an
Idof1 - We can find Sam's courses by looking in the
StudentCoursesfor the records that match hisStudentId
Example 2: ASP.NET MVC
ASP.NET MVChas anIdof 2- We can find all the students enrolled in the ASP.NET MVC course by checking the
StudentCoursestable
How many students are in the ASP.NET MVC course?