Interval expressions

This section covers interval expression evaluation rules.

An interval evaluates to an INTERVAL data type.

MAIN
  DEFINE r, c INTERVAL HOUR TO MINUTE
  LET c = "12:45"
  LET r = c + ( DATETIME(14:02) HOUR TO MINUTE - DATETIME(10:43) HOUR TO MINUTE )
END MAIN
The operands of an interval expression must be one of:

If an interval expression includes an operand whose value is not an interval data type, the runtime system attempts to convert the value to an interval value following the data conversion rules.

If an element of an integer expression is NULL, the expression is evaluated to NULL.