if (DBIdentifier.isEmpty(uniqueName)) {
uniqueName = dict.getValidUniqueName(DBIdentifier.newConstraint("UNQ"), table);
}
Unique u = table.addUnique(uniqueName);
for (DBIdentifier columnName : _uniqueColumnNames) {
if (!table.containsColumn(columnName, _conf.getDBDictionaryInstance()))
throw new UserException(_loc.get("unique-missing-column",
columnName, table.getIdentifier(),
table.getColumnNames()));
Column col = table.getColumn(columnName);
u.addColumn(col);