MySQL + SQL · Lesson 12
Relational Database and RDBMS
What is a Relational Database?
A relational database stores data in tables (relations) made of rows and columns, where tables are linked using keys. The software managing it is an RDBMS (e.g. MySQL).
Table = Relation
| Relational Term | Common Term |
|---|---|
| Relation | Table |
| Tuple | Row |
| Attribute | Column |
| Degree | Number of columns |
| Cardinality | Number of rows |
Example
CREATE TABLE students (roll_no INT PRIMARY KEY, name VARCHAR(50), class_id INT);
CREATE TABLE classes (class_id INT PRIMARY KEY, class_name VARCHAR(20));students.class_id links to classes.class_id — a relationship.
Summary
- Relational database = data in linked tables.
- RDBMS software manages it; MySQL is the most popular free one.