What is the usage of the COALESCE function in Oracle?

In Oracle, the COALESCE function returns the first non-NULL value from the list of parameters. If all parameters are NULL, it will return NULL. The syntax of the COALESCE function is as follows:

Combine the values from value1 to valuen.

The values value1, value2, …, valuen are the values to be compared. The COALESCE function will compare them in the order specified and return the first non-NULL value. For example:

The result from the above code will be ‘A’.

The result will be ‘C’ in this case from the given SQL query.

The result is NULL.

The COALESCE function is very useful when dealing with conditional expressions, as it can simplify SQL statements and improve readability.