condition that applies to multiple lines before update is made in another table - sql

Question

I have two tables, one table is linked by a foreign key to the other.
I need to create an update statement that would update table one based on a condition in table two. However, the conditions have to relate to one or more lines in table two.
Example - Table Two
Order A
line 1 = open (status column)
line 2 = closed (staus column)
When line 1 is also closed (same order number - in this case A), the condition is met so the order will then be closed (updated to closed) in the other table. Table on only has header information (no multiple lines).
I am having trouble with righting a condtion that looks at multiple lines in table two (all lines have to be closed) before the update to table one is made.
Any helpful suggestions would be appreciated.

Answer 1

Assuming that (1) the key name is ordernum, and (2) EVERY table1 entry has at least one entry in table2, this is a simple query that should work for you. Basically, the not exists clause is testing that there are no open lines in the second table.
update table1
set table1.status = 'closed'
where table1.status = 'open'
and not exists
(select 1
from table2
where table2.ordernum = table1.ordernum
and table2.status = 'open')
This may need tweaked further based on your business requirements.
Update based on user request: You could try this, but performance may take a hit, I've not tested it:
update table1
set table1.status = 'closed',
table1.count_lines =
(select count(1)
from table2 y
where y.ordernum = table1.ordernum
)
where table1.status = 'open'
and not exists
(select 1
from table2 z
where z.ordernum = table1.ordernum
and z.status = 'open')
Update 2: Try this from your last comment. You are wanting to update the ZORDER table with the sum of all the line item prices. So you must UPDATE ZORDER, not ZORDERLINE. The total is found by summing EXTENDED_PRICE on all ZORDERLINE rows that match the order id. There may be some additional business logic needed in the first sub-query (eg., if you need to exclude certain statuses like canceled items), but this should get you very close.
UPDATE zorder
SET zorder.status = 3,
zorder.total =
(SELECT SUM(Y.EXTENDED_PRICE)
FROM ZORDERLINE Y
WHERE Y.order_id = zorder.order_id)
WHERE zorder.status = 1
and not exists
(select 1
from zorderline z
where z.order_id = zorder.order_id
and z.status = 1)