What is the significance of NULL value and why should we avoid permitting null values?
Null
means no entry has been made. It implies that the value is either
unknown or undefined.We should avoid permitting null values because
Column with NULL values can't have PRIMARY KEY constraints. Certain
calculations can be inaccurate if NULL columns are involved.
What is SQL whats its uses and its component ?
The
Structured Query Language (SQL) is foundation for all relational
database systems. Most of the large-scale databases use the SQL to
define all user and administrator interactions. It enable us to retrieve
the data from based on our exact requirement. We will be given a
flexibility to store the data in our own format.
