HOUR/MINUTE/SECOND(t) 
HOUR(t), MINUTE(t) and SECOND(t) are functions (extraction) that extract the hour, minute and second from the specified date or time stamp value.
Value t: When used in a function, the expression t must supply a time value, a time stamp value, or an alphanumeric value that matches the current time or time stamp format.
t |
Result of the Function |
|---|---|
HOUR(t), MINUTE(t) or SECOND(t) |
Numeric value (hours, minutes, and seconds) |
t is a NULL value |
NULL value |