SQL & PL/SQL

Hi I have written the below query to get the fields below as an out put but am getting the error missing keyword..am not understanding where did i missed..i have done step by step query analysis..but could not find the error.

Please help me in resolving the issue.

Expected output Columns :*

COUNTRY , TRN_TYPE ,SKU ,BIX_Customer ,PERIOD ,CURRENTSTOCK ,STOCK_VALUE ,SALES ,SALES_VALUE ,TARGET


Query :_


select (case when a.country is null then b.country when b.country is null then c.country else a.country end) AS COUNTRY,
(case when a.Sale_Type is null then b.Stk_type when b.stk_type is null then c.Stk_type else a.Sale_Type end) AS TRN_TYPE,
(case when a.sku is null then b.sku when b.sku is null then c.sku else a.sku end) AS SKU,
(case when a.bix_customer is null then b.bix_customer_code when b.bix_customer_code is null then c.bix_customer_code else a.bix_customer end)AS BIX_Customer ,
(case when a.period is null then TO_number(b.period) when b.period is null then TO_NUMBER(c.period) else a.period end) AS PERIOD,
nvl(b.CURRENTSTOCK,0) AS CURRENTSTOCK,
nvl(b.stock_value,0) AS STOCK_VALUE,
nvl(a.sales,0) AS SALES,
nvl(a.SALES_VALUE,0) AS SALES_VALUE,
nvl(c.TARGET_QTY,0) AS TARGET
from

(select UPPER(c.cust_country_name) AS COUNTRY,
DECODE(ds.account_key,7156,'SAMPLE',7157,'BONUS',7485,'SALE') AS Sale_Type,
substr(i.item_code,7) AS SKU,
c.bix_customer_code AS BIX_Customer,
ds.descr as descr ,
ds.period as period,
sum(ds.quantity) AS SALES,
sum(case when ds.local_value is null then ds.euro_value else ds.local_value END) AS SALES_VALUE
FROM distributor_sales ds, customer c, item i
where ds.customer_key=c.customer_key
and ds.item_key= i.item_key
group by ds.period,
ds.account_key,
c.cust_country_name,
substr(i.item_code,7),
c.bix_customer_code,
ds.descr) a
full outer join
(SELECT UPPER(b.cust_country_name) AS COUNTRY,
DECODE(s.stock_type,'SALE','SALE','SALES','SALE','BONUS','BONUS','SAMPLE','SAMPLE') AS Stk_type,
substr(c.item_code,7) AS SKU,
s.descr as descr,
s.period as period,
b.bix_customer_code,
sum(s.CLOSING_STOCK) CURRENTSTOCK,
sum(s.closing_stock*s.cif_price) STOCK_VALUE
FROM STOCK s, customer b, item c
WHERE s.customer_key=b.customer_key
and s.item_key= c.item_key
group by
s.descr,
s.stock_type,
s.period, b.bix_customer_code,b.cust_country_name,substr(c.item_code,7) ) b
full outer join
(SELECT UPPER(cu.cust_country_name) AS COUNTRY,
DECODE(t.description,'SALES TARGET','SALE') AS Stk_type,
substr(it.item_code,7) AS SKU,
t.channel as channel,
t.period as period,
cu.bix_customer_code as bix_customer_code,
sum(t.quantity) TARGET_QTY
FROM sales_target t, customer cu, item it
WHERE t.customer_key=cu.customer_key
and t.item_key= it.item_key
group by
t.channel,
t.description,
t.period, cu.bix_customer_code,cu.cust_country_name,substr(it.item_code,7) ) c

on a.SKU=b.SKU
and a.sku=c.SKU
and b.sku=c.SKU
and a.BIX_Customer=b.bix_customer_code
and a.BIX_Customer=c.bix_customer_code
and b.bix_customer_code=c.bix_customer_code
and a.Sale_Type=b.Stk_type
and a.Sale_Type=c.Stk_type
and b.Stk_type=c.Stk_type
and a.descr=b.descr
and b.descr=c.channel
and a.descr=c.channel
and a.country=b.country
and a.country=c.COUNTRY
and b.country=c.COUNTRY
and a.period=b.period
and a.period=c.period
and b.period=c.period;