If your ODBC data-source tables have at least one unique index, they can be used to support operations such as backward and forward scrolling and accurate cursor positioning through the FIND CURRENT, PREV, and LAST statements. If a table does not have a unique index, you can only scroll forward through its data.

If an ODBC data-source table does not have a unique index, you can designate an index to serve as the unique index for the schema holder. An index that you designate as unique in the schema holder must be unique with respect to the data in the data source; otherwise, you receive run-time errors. See The DataServer Tutorial for instructions on using the Data Dictionary to designate unique indexes.

ODBC data-source views and result sets from stored procedures do not have unique indexes. Just as for tables, you can use the Data Dictionary to create a unique index in the schema holder based on fields in a view or result set so that you can browse data accessed through views or stored procedures.