Which function would return the name of the day from a date?

The function that would return the name of the day from a date is known as DATENAME. This function is specifically designed to extract and return a specific part of a date as a string, including the names of the days of the week. When you use this function, you can specify that you want to retrieve the day component, and it will provide the full name of the day (like 'Monday' or 'Tuesday') for the given date.

In contrast, other functions like DAY and DATEPART serve different purposes. DAY retrieves the numerical day of the month from a date (for example, the 15th of the month), while DATEPART returns a specific part of the date in numerical form, such as the day number, week number, or year. WEEKDAY is generally used to obtain the numerical representation of the day of the week (like 1 for Sunday, 2 for Monday, etc.) rather than the full name.

Thus, when looking for a function to provide the actual name of the day associated with a specific date, DATENAME is the most appropriate choice.