Null values

The STL format provides support for null values (see Section ). A null value for a field in an STL table is indicated by inserting the string `<null>' at the appropriate place in the input file. When CURSA reads this string it will interpret it as a null value. Actually, if CURSA encounters any value for a field which it cannot interpret given the data type of the column (such as a string containing alphabetic characters in a field for an INTEGER column) then the field is interpreted as null. However, when preparing STL files I recommend that you indicate nulls using the string `<null>'. This string is recognised as indicating a null value even for CHARACTER columns.

When CURSA writes an STL catalogue null fields in the table are represented by the string `<null>'.

Null values are not permitted in the KAPPA variant of the STL format (see Appendix ).