I need to create a table which has columns
Div_no Reg_no Area_no store_no Trans_key sales_units operator_id total sales

we have the following tables
Table-A
Columns-Div_no Reg_no Area_no store_no

Table-B
Columns -Trans_key store_no sales_units

Table-C
Columns -Trans_key store_no sales_units

Table D
Columns-Trans_key store_no operator_id

Table E
Columns-Trans_key store_no operator_id


Table F
Columns-Trans_key store_no operator_id

I need all the trans_key from B and C so i need a UNION of the join to A and B and A and C.I plan to put it in a staging table.I need to do a outer join from A to B because all the store numbers are not present in A .Same goes for A and C .The total sales will be a sum of sales_units group by trans_key.
Then from that staging table i need to join to D,E and F (combined) to get the operator ids and then finally all the data has to be present in a target ETL table.
Could anybody plz help me in framing the query for this?