N,

You don't seem to have any data on which to join the tables. Where does Item_code show up in any of the other tables? Are their invoice details tables that have the Item_code in them? The other three tables seem to be able to be joined on InvNo however in the last two if the records amy be in one or the toher you need to use a LEFT OUTER JOIN condition in your select (the select belwo ignores the first table because there is no join condition available for it) ...

SELECT * ;
  FROM Table2 ;
  LEFT JOIN Table3 ON Table2.InvNo = Table3.InvNo ;
  LEFT JOIN Table4 ON Table2.InvNo = Table4.InvNo ...