A relation has several properties that make a relation different from a table. Some of these properties are discussed below:

1. There is no duplication of tuples in a relation:
A relation is a mathematical set (of tuples), and sets in mathematics by definition do not include duplicate elements. So a relation cannot contain any duplicate tuples. It means that two (or more) identical rows (or records) cannot exist in a relation. Each row in a relation must be unique. For example, in a student relation, there cannot two records (rows) for the same student. Uniqueness in a relation is guaranteed by assigning the primary key for each relation.

2. All attribute values of relation are atomic:
According to this property of relation, each cell of a relation (table) contains only one value (never a collection of several values). You can say that each value in a tuple is an atomic value which cannot be divisible into components. The composite and multi-valued attributes (or repeating groups) are not allowed. Multi-valued attributes must be represented by separate relations. A relation satisfying this condition is said to be normalized (or equivalent to first normal form). For example, in a student relation, you must have to write a single telephone number of a student (More than one telephone numbers separated by commas is not allowed). Similarly, there should be three attributes for student name such as First-Name, Middle-Name, and Last-Name.

3. All attribute values of a relation must come from the same domain:
The values for attributes must be within the acceptable range. For example, in a student relation all entries in "Marks" attribute must be from the domain that defme's student marks (such as between 0 and 200).