Relations, Tuples, and Attributes

A teammate sends you a message: "the Student relation has degree 4 and cardinality 8000, and CGPA is nullable."

Every word in that sentence is precise. None of it is obvious.

This lesson gives you those words. Chapters 6 and 7 use all of them, so it is worth being exact here rather than approximate.

The three core words

A relation is a table. It has a name, a fixed set of named columns, and a set of rows. Student is a relation.

An attribute is a named column. roll_no, name, cgpa and dept are the four attributes of Student.

**A tuple is a row