The following notes apply when you use the Oracle server predicate: o If tables A and B are joined by multiple join conditions, then the plus (+) operator must be used in all these conditions. o The plus operator can be applied only to a column, not to an arbitrary expression. However, an arbitrary expression can contain a column marked with the plus operator. o A condition containing the plus operator cannot be combined with another condition using the OR logical operator. o A condition cannot use the IN comparison operator to compare a column marked with the plus operator to another expression. o A condition cannot compare a column marked with the plus operator to a subquery. o If the WHERE clause contains a condition that compares a column from table B to a constant, then the plus operator must be applied to the column such that the rows from table A for which Oracle Rdb has generated NULLs for this column are returned. o In a query that performs outer joins of more than two pairs of tables, a single table can only be the null-generated table for one other table. For this reason, you cannot apply the plus operator to the column of table B in the join condition for tables A and B and the join condition for tables B and C.