Date and time comparisons

Three types are associated with the date and time functions: date, time, and timestamp.

The timestamp type is implicitly converted to the date and time types and can therefore be passed to any of the date/time functions. For example, although the signature for the next_month() function indicates that the function takes an input value of type date, it is permissible to pass an input value of type timestamp to the next_month() function.

The date type is implicitly converted to the timestamp type but not the time type. Therefore, you can supply the date type to any function that takes either a date or a timestamp type.

You cannot convert values of type time into anything; therefore, you can supply them only to functions that take this type.