DBMS First normal form (1NF)
As per the rule of first normal form, an attribute (column) of a table cannot hold multiple values. It should hold only atomic values.
Example
Suppose a company wants to store the names and contact details of its employees. It creates a table that looks like this:
Two employees (Jon & Lester) are having two mobile numbers so the company stored them in the same field as you can see in the table above.
This table is not in 1NF as the rule says “each attribute of a table must have atomic (single) values”, the emp_mobile values for employees Jon & Lester violates that rule.
To make the table complies with 1NF we should have the data like this:
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