MDAC 2.5 SDK - OLE DB Programmer's Reference
Appendix C: OLE DB Properties
Property group: Rowset
Property set: DBPROPSET_ROWSET
Type: VT_BOOL
Typical R/W: R/W
Description: Unique Rows
| Value | Meaning |
| VARIANT_TRUE | Each row is uniquely identified by its column values. |
| VARIANT_FALSE | Rows in the rowset may or may not be uniquely identified by their column values. |
If this property is set to VARIANT_TRUE when opening the rowset, the provider adds additional columns, if necessary, to ensure that each row is uniquely identified by its values. These additional columns appear at the end of the rowset; have a DBID of type DBKIND_GUID_PROPID, DBKIND_PGUID_PROPID, DBKIND_GUID_NAME, or DBKIND_PGUID_NAME; and the guid (or pguid) element is (or points to) DBCOL_SPECIALCOL. These columns typically are not displayed to the user but are used by components such as update services to uniquely identify a row.
The provider optionally may duplicate existing columns in the rowset to ensure that key columns are included.
If this property is set to VARIANT_TRUE and the provider supports the optional IColumnsRowset metadata column DBCOLUMN_KEYCOLUMN, the set of columns that uniquely identify the row have a value of VARIANT_TRUE in the DBCOLUMN_KEYCOLUMN column returned by IColumnsRowset. This may be a subset of the columns in the row, or all of the columns if the provider cannot determine a proper subset that uniquely identifies the row.