What is Atomic Relation in First Normal Form

1NF requires that every attribute position in every tuple in every relation contains a single value of the appropriate type. The types can be arbitrarily complex. In fact, the types can be relations. (CJ Date's book Database in depth: relational theory for practitioners treats this issue in a way that's pretty easy to understand.)

"Atomic" has never really meant "indivisible", which is why that term is finally falling out of favor. Loosely speaking, "atomic" means if a value has component parts, the dbms either ignores the existence of those parts, or it provides functions to manipulate them. For example, a timestamp value has these parts.

• Year
• Month
• Day
• Hours
• Minutes
• Seconds
• Milliseconds

That kind of value is obviously divisible, and all database management systems provide functions to manipulate those parts. They also provide a way to select a timestamp as a single value. (Which, of course, it is.)

"Atomic" refers to Codd's original notion from 1969 that each attribute in each tuple within a relation should consist of a single value and not allow multivalued structures of the kind supported in databases like the CODASYL model.

In modern SQL DBMSs atomicity isn't really an issue. SQL tables do not allow multivalued columns and values are always "atomic".

Atomic means data which cannot be divided further.

Rule of atomicity:

• rule 1: a column with atomic data can't have several values of the same type of data in the same column.
• rule2: a table with atomic data can't have several columns with the same datatype.

Like fullname column can't say that it could be atomic because it can be further divded into lastname, firstname. A column with interest could also be divided further, so a column which can't be divided is known as atomic.