Time function 

A time function is a function that is applied to time or timestamp values or supplies a time or timestamp value as a result.

Syntax

<time function> ::=
  ADDTIME    ( <time or timestamp expression>, <time expression> )
| SUBTIME    ( <time or timestamp expression>, <time expression> )
| TIMEDIFF   ( <time or timestamp expression>, <time or timestamp expression> )
| MAKETIME   ( <hours>, <minutes>, <seconds> )

time or timestamp expression, time expression, hours, minutes, seconds

ADDTIME/SUBTIME(t,a), TIMEDIFF(t,s), MAKETIME(h,m,s)

A variety of date and time formats (ISO, USA, EUR, JIS, INTERNAL) are available for processing date and time values.