What are the functions of the coalesce function in SQL?

In SQL, the COALESCE function is used to return the first non-null expression in a list of parameters. It is used for:

1. Return the first non-empty value in the parameter list.
2. If all values in the parameter list are empty, return NULL.
3. It can accept an arbitrary number of parameters.
4. Can be used as an alternative to the NVL function for handling NULL values.

In general, the COALESCE function is mainly used to handle NULL values, ensuring that errors do not occur when processing data.