Nulls are special values of the data types supported by Process Engine (PE). Only type time allows null values. The only valid operations you can perform on null variables are assignments and equality comparisons.
Following are brief descriptions of the functions that can be used with null values. For more detailed information about a specific function (such as usage and syntax), click the function name.
Function | What it does |
---|---|
null() |
Returns a null time value. |
Returns the boolean value true if the expression evaluates to a null value. |
This time function returns a null time value.
Use the following syntax:
null(time)
where time is the data type. Time is the only supported data type for this function.
This boolean function returns true if the input expression evaluates to a null value; otherwise, the is_null function returns false.
Use the following syntax:
is_null(time_expr)
where time_expr is an expression of type time.
TIP If it is likely that an expression evaluates to null, always test it using the is_null function, since most operations on a null value are invalid.