How to map fields different tables

[Chandu9]

We have two tables,

-in first table contains customer id,2nd tables we have 4 fields 

1)zu partner num,2)ship to code 3)sold to code,4)Bill to code

First link using'zu partner id'and get account names,for the remaining unmaped unmaped accounts,use ship to code,for the remaining unmaped accounts,use sold to code,names,for the remaining unmaped  accounts,use ship to code Bill to code.

To get all the account names using above logic.

[Taoufiq_Zarra]

@Chandu9  can you share a sample data and the expected output ?