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What is the significance of NULL value and why should we avoid permitting null values?NULL value means that no entry has been made into the column. It states that the corresponding value is either unknown or undefined. It is different from zero or "". They should be avoided to avoid the complexity in select & update queries and also because columns which have constraints like primary or foreign key constraints cannot contain a NULL value.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.
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