This property is used to enable autoincrement key field functionality in Oracle, InterBase and other databases that support special database objects used to generate unique (autoincrementing) values. With SQL Server, Access and Sybase, the autoincrement (identity) is assigned automatically by the database and can be retrieved with a special SQL command, see the SqlDialectInfo.IdentityColumnLastValueSelect property. In Oracle and Interbase, setting the key value is not done automatically by the database. It can be done either automatically by C1DataObjects, if you set SqlDialectInfo.IdentityColumnRetrieveMode = BeforeInsertCommand, or by a trigger, in which case you set IdentityColumnRetrieveMode = AfterInsertCommand. In both cases, in addition to setting the IdentityColumnLastValueSelect property that retrieves the autoincremented value, you must set the AutoIncrementSequenceName property to the name of the object generating the value, a sequence in Oracle, a generator in Interbase.

Reference

Field Class
Field Members
Table Fields
Keys Assigned by Server or Database
IdentityColumnLastValueSelect Property