🚀 go-pugleaf

I am trying to make an updateable query which uses a subquery to 
calculate one of its columns. It seems to work ok except I get the same 
value in each row for "Previously Invoiced". The problem appears to be 
in the (DOCLINE.ITEM_ID = DOCLINE.ITEM_ID). What I'm trying to achieve 
is that the subquery should recalculate each row using the main row's 
Item_id. Is it possible to do this? If so, how?

Many thanks

Mitch

SELECT
DOCLINE.DOCLINE_ID,
DOCLINE.ITEM_ID,
DOCLINE.DOCLINE_QTY,
DOCLINE.DOCLINE_TOTAL_VALUE,
(
SELECT SUM( DOCLINE.DOCLINE_TOTAL_VALUE ) FROM DOC
INNER JOIN DOCLINE ON (DOC.DOC_ID = DOCLINE.DOC_ID)
WHERE
(DOC.DOC_ID < :DOC_ID) AND (DOCLINE.ITEM_ID = DOCLINE.ITEM_ID) AND 
(DOC.PROJ_ID = :PROJ_ID)
)
AS PREVIOUSLY_INVOICED,
LOC_NAME

FROM LOC
  RIGHT OUTER JOIN ITEM ON (LOC.LOC_ID = ITEM.LOC_ID)
  INNER JOIN DOCLINE ON (ITEM.ITEM_ID = DOCLINE.ITEM_ID)

WHERE
DOCLINE.DOC_ID = :DOC_ID