Datetime expressions

This section covers date-time expression evaluation rules.

A datetime expression evaluates to a DATETIME data type.

MAIN
  DEFINE r, c DATETIME YEAR TO SECOND
  LET c = CURRENT YEAR TO SECOND
  LET r = c + INTERVAL( 234-02 ) YEAR TO MONTH
END MAIN

The operands of a datetime expression can be one of:

• A datetime literal.
• A character string literal representing a datetime with the format YYYY-MM-DD hh:mm:ss.fffff.
• A variable or constant of DATETIME type.
• A function returning a single datetime value.
• A unary + or - sign associated with an interval expression.
• A CURRENT expression.
• An EXTEND expression.

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

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