Show the first, middle and last name of each person together, as one column, in the following way:

Firstname Middlename LASTNAME

Firstname is the first name and Middlename is the middle name - first letter in uppercase, rest in lowercase. LASTNAME is the last name in uppercase. Name the column full_name

Show this information only for those people whose last_name is at least 7 characters long. Make sure to handle properly the people who have no middle name. Show an empty string instead of a NULL middle name.