Question

The following sql query below produced this result

cust table

CUST_ID     AC_NO      NAME            AREA  SALES
---------- ---------- ------------------------- ---
C001       A30045     Smiths Heavy       1   R001
C002       A30145     Heavy jonps        1   R001
C003       A30046     dangote flour      1   R002
C004       A30047     OAU ife            2   R002


Area Table

AREA_NUMBER AREA_NM  AREA_Dp
----------- ---------- ----------
      1 North      Leeds
      2 South      Newcastle
      3 East       Surrey
      4 West       London



Area_geo Table


SALE REPP_   AREAA_ID AREAM AREAMANAGER_NAME
---- ----- ---------- ----- -------------------
SG01 R001           1 R110  mandy Jay
SG02 R002           2 R110  mandy Jay
SG03 R003           3 R111  Kay sole
SG04 R003           3 R111  Kay sole
SG05 R003           3 R111  Kay sole
SG06 R001           4 R110  mandy Jay




  select cust.*,
  area.AREA_Nm,area.AREA_Dp
   from area inner join cust on
   area.area_number=customer.area
   ORDER BY customer.Cust_ID;

Result

 CUST_ID    AC_NO      NAME            ADDRESS         AREA  SALES  AREA_N  AREA_Dp
 ---------- ---------- -------------- ------------------------- ---------- ----- ---
 Ac003       A30046     dangote flour  court Estate     1    R002   North      Leeds
 Ac004       A30047     OAU ife        4 Abanishe       2    R002   South      Newcastle

my intension is to further include the Areamanager_name into the above result from the table below. the table below however has a common attribute (Area_ID) to the above result (Area)

Table Area_Geo

SALE REPP_   AREA_ID  AREAM   AREAMANAGER_NAME
---- ----- ---------- ----- ----------------
SG01 R001        1    R110    mandy Jay
SG02 R002        2    R110    mandy Jay
SG03 R003        3    R111    Kay sole
SG04 R003        3    R111    Kay sole
SG05 R003        3    R111    Kay sole
SG06 R001        4    R110    mandy Jay

expected result

 CUST_ID    AC_NO      NAME            ADDRESS         AREA  SALES  AREA_N   AREA_dp Areamanager
 ---------- ---------- -------------- ------------------------- ---------- ----- ---
 Ac003       A30046     dangote flour  court Estate     1    R002   North    Leeds     mandy Jay
 Ac004       A30047     OAU ife        4 Abanishe       2    R002   South    Newcastle mandy Jay

Answer 1

I think the below should do it, I reformatted it a bit so I could read it a bit easier. You
would need an outer join if sometimes you didn’t have an area manager.

SELECT cust.*
      ,area.area_Nm
      ,area.AREA_Dp
      ,area_geo.Areamanager_name
FROM area inner join cust     on area.area_number = customer.area
          inner join area_geo on area.area_number = area_geo.area_id
ORDER BY customer.Cust_ID;

edit in response to comment :-

The problem of double values is caused by the fact that the area_geo table can have ( and in the case of area_id 3 appears to have ) duplicate values for an area_id. When you do a join a row is returned for each row in the table, so for area_id 3 rows would be returned every time. You could do use a sub query

SELECT cust.*
      ,area.area_Nm
      ,area.AREA_Dp
      ,(SELECT DISTINCT area_geo.Areamanager_name
        FROM   area_geo
        where  area.area_number = area_geo.area_id) Areamanager_name
FROM area inner join cust     on area.area_number = customer.area
ORDER BY customer.Cust_ID;

But if there are different values of Areamanager_name for the same area_id, this query will fail. Ideally I think you need to use a more suitable table to retrieve the areamanager_name, or if there isn’t one normalize your database so that there is only 1 record in area_geo for each area_id.