ТЕМА:

MERGE INTO table1 dest
  USING (SELECT field1, field2, field3 FROM table2) source1
      ON (dest.field1 = source1.field1)
      WHEN MATCHED THEN
          UPDATE SET dest.field2 = source1.field2,
                                   dest.field3 = source1.field3
          WHERE source1.field2 IS NOT NULL
          DELETE source1.field2 IS NULL
      WHEN NOT MATCHED THEN
           INSERT (dest.field1, dest.field2, dest.field3)
           VALUES (source1.field1, source1.field2, source1.field3)
           WHERE source1.field2 IS NOT NULL