buff.appendExceptFirst(", ");
buff.append(c.getSQL());
}
buff.append(") C WHERE NOT EXISTS(SELECT 1 FROM ").
append(refTable.getSQL()).append(" P WHERE ");
buff.resetCount();
int i = 0;
for (IndexColumn c : columns) {
buff.appendExceptFirst(" AND ");
buff.append("C.").append(c.getSQL()).append('=').
append("P.").append(refColumns[i++].getSQL());