If you pass a null value as a parameter or if the result of an expression is null, the value is treated as a null indicator. For example, if the result of an expression is null and the return datatype is String, a string is returned with a value of null. You can check the result of an expression by using the isResultNull method.

You must convert input parameters with a Date datatype to a String before you can use them in an expression. To use the string in an expression as a Date datatype, use the to_date() function to convert the string to a Date datatype.

You can get the result of an expression that returns a Date datatype as a String or long datatype.

To get the result of an expression that returns a Date datatype as a String datatype, use the getStringBuffer method. To get the result of an expression that returns a Date datatype as a long datatype, use the getLong method.