This is the table that stores the data I need:
CREATE TABLE COST
(
  PART_ID               VARCHAR2(9 BYTE)        NOT NULL,
  BEGIN_DATE            DATE,
  COGNIZANCE_CODE       VARCHAR2(2 BYTE),
  MATERIAL_CNTL_CODE    VARCHAR2(1 BYTE),
  UNIT_PRICE_AMT        NUMBER(14,2),
  END_DATE              DATE,
  REPAIR_NET_PRICE_AMT  NUMBER(10,2),
  LAST_ALTER_TS         DATE
)

CREATE UNIQUE INDEX COST_PK ON COST
(PART_ID, BEGIN_DATE)

ALTER TABLE COST ADD (
  CONSTRAINT COST_PK
 PRIMARY KEY
 (PART_ID, BEGIN_DATE)


This is sample data in the cost table above:
PART_ID		BEGIN_DATE	COGNIZANCE_CODE	MATERIAL_CNTL_CODE	UNIT_PRICE_AMT	END_DATE	REPAIR_NET_PRICE_AMT	LAST_ALTER_TS
000000158	5/25/2006	                 9L 	1584.47	10/14/2006    0	5/23/2006 10:28:09 PM
000000158	10/1/2002		9L	1902.02	10/27/2003     0	5/18/2003 7:29:00 PM
000000158	12/13/2006	9B	1698.35		     0	12/12/2006 1:48:59 AM
000000158	10/28/2003	9L	1572.42	5/24/2006	     0	10/27/2003 11:21:39 AM
000000158	10/15/2006	9L	1698.35	12/12/2006     0	10/14/2006 11:33:00 AM
000000158	10/1/1999		9L	2188.91	12/31/2001	12/1/2004 4:13:37 PM
000000158	1/1/2002		9L	2526.17	9/30/2002		 12/1/2004 4:13:37 PM
000000165	1/1/2004		D	66832			12/1/2004 4:13:37 PM
000000165	10/1/1999		D	50940.69	12/31/2001	12/1/2004 4:13:37 PM
000000165	1/1/2002		D	60980.96	12/31/2002	12/1/2004 4:13:37 PM
000000165	1/1/2003		D	66912	12/31/2003	12/1/2004 4:13:37 PM

This is the table I will loading the above data into - I only want to insert into this table, the latest cost record, for each part record, in the above cost table (I highlighted these records red above):
CREATE TABLE PART
(
  PART                          CHAR(9 BYTE)    NOT NULL,
  COG                           CHAR(2 BYTE),
  FSC                           CHAR(4 BYTE),
  MCC                           CHAR(1 BYTE),
  REPAIR_NET_PRICE              NUMBER(10,2),
  ROUTING_ID_CODE               CHAR(3 BYTE),
  SECURITY_CLASSIFICATION_CODE  CHAR(1 BYTE),
  SMIC                          CHAR(2 BYTE),
  UNIT_OF_ISSUE                 CHAR(2 BYTE)    NOT NULL,
  UNIT_PRICE                    NUMBER(12,2)    NOT NULL,
  ACQUISITION_ADVICE_CODE       CHAR(1 BYTE)    NOT NULL,
  QUANTITY_PER_UNIT_PACKAGE     CHAR(1 BYTE)    NOT NULL,
  SOURCE_OF_SUPPLY              CHAR(3 BYTE)    NOT NULL,
  SLC                           CHAR(1 BYTE)    NOT NULL,
  ITEM_NAME                     VARCHAR2(50 BYTE)
)

CREATE INDEX PART_PK ON PART
(PART)

ALTER TABLE PART ADD (
  CONSTRAINT PART_PK
 PRIMARY KEY
 (PART)


Using your example, I compiled the below statement. It appears to select the correct information:
select part_id, cognizance_code, 
       material_cntl_code, unit_price_amt
       repair_net_price_amt
from (
    select part_id, begin_date, cognizance_code, 
       material_cntl_code, unit_price_amt,
       repair_net_price_amt,
      row_number () over (partition by part_id order by begin_date desc) rn
      from cost)
where rn = 1

When I add the below insert statement above the select statement
insert into part_stage
   (part, cog, mcc, unit_price, repair_net_price)

Making the total statement look like the below - I get an ORA-00947: not enough values message.

insert into part_stage
   (part, cog, mcc, unit_price, repair_net_price)
select part_id, cognizance_code, 
       material_cntl_code, unit_price_amt
       repair_net_price_amt
from (
    select part_id, begin_date, cognizance_code, 
       material_cntl_code, unit_price_amt,
       repair_net_price_amt, 
       row_number () over (partition by part_id order by begin_date desc) rn
      from cost)
where rn = 1

What do you suspect is the problem?  Thanks, Sandy