This operator subtracts the second operand from the first and returns the result. Depending on the value types of the two operands, the value type of the result can be the same as one of the two operands or even a completely different value type, as in the case of a date minus a time, which returns a datetime.
Note the special meaning of the "-" operator in connection with dates:
number1 - number2 // Returns number number - currency // Returns currency time - number // Returns time date - number // Returns date datetime - number // Returns datetime time - number // Returns time
depends on operand value types
21 - 21 // Returns 0 21 - $21 // Returns $0 time(12,00,00) - 73 // Returns 11:58:47 date(2005,12,12) - 42 // Returns 10/31/2005 datetime(2005,12,12,5,5,5) - 42 // Returns 10/31/2005, 5:05:05 a.m.