External datatypes

It is possible to define additional datatypes that map integers to the possible values of a column; these datatypes are called external datatypes, because they are defined externally to the present schema.

Syntax

In order to use a datatype that has been defined in a previously loaded schema, the current schema must contain a statement of the following structure.

data type datatype is external datatype ;

Examples

The following examples show the datatype declaration.

data type boolean is external boolean
data type entityTypes is external entityTypes

After you have made these declarations you can use the datatypes boolean and entityTypes in the current schema, provided that they have also been defined in a previously loaded schema.