finding specific customers in contract table - sql

Question

I am working with MS SQL and need help creating a query.
I have a table called CustomerContracts, in it is multiple lines per item# for specific customers.
For example real data
item cust_num
x 1156
x 3924
x 7565
x 84339
x 104365
x 106066
x 107377
x 118691
y 1156
y 3924
y 7565
y 84339
y 104365
y 106066
y 107377
So what I need to do is search the table by item number and a specific customer number and return the item if that customer number does not exist as a record for that item.
So, in this case I am checking all item records for the cust_num of 106066 and 118691 if the item does not contain both customers then I want it to be included in my results so in this cause item X would not show up, but item Y would.
I think I need to do some type of count. I have tried using NOT IN(002,003) no luck.
Suggestions?
to satisfy my attempt at this. I have tried at least 8 different ways, this is the latest attempt.
select 'Cust Does not exist' as Status,
i.item as item,
i.description as description,
t.numcusts
From
item i inner join (select count(cust_num) as numcusts,item
from itemcust
where cust_num NOT IN ('106066','118691')
group by item) t on t.item = i.item
where i.stat = 'A' and t.numcusts > 0
order by i.item,i.description
did not work. So, I am still trying to resolve it. I was able to develop a sort of solution using imbedded queries in Access, but can't get the sql it created to port over.

Answer 1

I am guessing that you have multiple records for a customer. You want customers where the table has no record for a given item. One approach is to use group by and having:
select cc.cust_num
from CustomerContracts cc
where c.cust_num in ('001', '002')
group by cc.cust_num
having sum(case when cc.cust_item_num in ('aaa') then 1 else 0 end) = 0;
Another approach is to use not exists:
select cc.*
from CustomerContract cc
where c.cust_num in ('001', '002') and
not exists (select 1 from CustomerContracts where cust_item_num in ('aaa'));
The first gives a list of customer number. The second gives all the records for those customers.
EDIT (based on edit to question):
The question is about items not customers. A modification to the first approach will work. If you only want items that have at least one of the customers, then use a where clause:
select cc.cust_item_num
from CustomerContracts cc
where c.cust_num in (106066, 118691)
group by cc.cust_item_num
having count(distinct c.cust_num) < 2;
If you want all items (even where neither customer appears), then count each customer match separately in the having clause:
select cc.cust_item_num
from CustomerContracts cc
group by cc.cust_item_num
having sum(case when c.cust_num = 106066 then 1 else 0 end) = 0 or
sum(case when c.cust_num = 118691 then 1 else 0 en) = 0;

Answer 2

Thanks for the help, but after 5 cups of coffee and 2 playlists I figured it out
select 'Cust Does not exist' as Status,
i.item as item,
i.description as description,expr1
From
item i RIGHT join (select itemcust.item,
sum(case when LTRIM(RTRIM(cust_num)) = '106066' or LTRIM(RTRIM(cust_num)) ='118691'then 1 else 0 end) as expr1
from itemcust
group by itemcust.item) t on t.item = i.item
where i.stat = 'A' AND expr1 <> 2
order by i.item,i.description
This gives me all the items that do not have both records or actually have them more than once.