The COALESCE function returns the first non-NULL value from a series of expressions. ... The result of the COALESCE function returns NULL only if all the arguments are null. The expressions can return any data type that can be cast to a common compatible data type.

What is coalesce () in SQL?

The SQL Coalesce and IsNull functions are used to handle NULL values. ... The SQL Coalesce function evaluates the arguments in order and always returns first non-null value from the defined argument list.

Why do we use coalesce function in Oracle?

The Oracle/PLSQL COALESCE function returns the first non-null expression in the list. If all expressions evaluate to null, then the COALESCE function will return null.