We can use SQL ISNULL to replace existing NULL values with a specific value. For example, we want to return Employee salary 10,000 if it is NULL in the Employee table. … We do not have any NULL value in the table now; therefore if we run the query with SQL Server ISNULL, it returns actual values of the rows.

Why is Isnull used in SQL?

We can use SQL ISNULL to replace existing NULL values with a specific value. For example, we want to return Employee salary 10,000 if it is NULL in the Employee table. … We do not have any NULL value in the table now; therefore if we run the query with SQL Server ISNULL, it returns actual values of the rows.

What is the use of null in database?

What is a SQL NULL value? In terms of the relational database model, a NULL value indicates an unknown value. If we widen this theoretical explanation, the NULL value points to an unknown value but this unknown value does not equivalent to a zero value or a field that contains spaces.