Select As Status If Subtable Lines Include Value - sql

Question

I have 2 Table named Order and OrderDetails
Order Table
orderID orderDate OrderUserId
1 10 01.01.2010 .....
2 20 05.05.2011 .....
OrderDetails Table
DetailID OrderIdOfDetail DetailProductID DetailStatusID
1 25 10 xxx 1
2 26 10 xxx 2
3 27 10 xxx 2
4 28 10 xxx 0
5 29 10 xxx 1
6 30 20 xxx 1
7 31 20 xxx 2
8 32 20 xxx 0
DetailStatusId for closed , pending, cancelled bla...
For example I want to select orderID : 10.
If detail lines include DetailsStatusID 1 select order Status as "Pending".
If detail lines include DetailsStatusID 2 select order Status as "Open".
If all DetailsStatusID is equal and 0 select order status as "Closed"
I tried "if exist" but couldn't success.
How can I do it ?

Answer 1

You can use a query like the following:
SELECT o.orderID,
CASE
WHEN MAX(CASE WHEN DetailStatusID = 1 THEN 1 ELSE 0 END) +
MAX(CASE WHEN DetailStatusID = 2 THEN 1 ELSE 0 END) +
MAX(CASE WHEN DetailStatusID = 0 THEN 1 ELSE 0 END) >= 2
THEN 'MultiStatus'
WHEN COUNT(CASE WHEN DetailStatusID = 1 THEN 1 END) > 0 THEN 'Pending'
WHEN COUNT(CASE WHEN DetailStatusID = 2 THEN 1 END) > 0 THEN 'Open'
WHEN MAX(DetailStatusID) = 0 THEN 'Closed'
END AS Status
FROM Order AS o
JOIN OrderDetails AS od ON o.orderID = od.OrderIdOfDetail
GROUP BY orderID
The query uses a CASE expression in order to calculate the Status field:
It first checks whether the order contains at least one record with DetailStatusID = 1. If it does 'Pending' is returned.
It then checks whether the order contains at least one record with DetailStatusID = 2. If it does 'Open' is returned.
It then checks whether all records of the group have DetailStatusID = 0. In this case 'Closed' is returned. I assume that DetailStatusID cannot take negative vaues.

Answer 2

This uses a left join to an derived table (subquery) that uses conditional aggregation to count the different DetailStatusId. This will also return a result of Other for Status if, for some reason, the OrderId has no corresponding details record.
select o.*
, [Status]=case
when od.Status0 > 0 and od.Status0 = od.DetailCount
then 'Closed'
when od.Status1 > 0
then 'Pending'
when od.Status2 > 0
then 'Open'
else 'Other'
end
from orders as o
left join (
select
OrderIdOfDetail
, DetailCount = count(*)
, Status0 = sum(case when DetailStatusId = 0 then 1 else 0 end)
, Status1 = sum(case when DetailStatusId = 1 then 1 else 0 end)
, Status2 = sum(case when DetailStatusId = 2 then 1 else 0 end)
from OrderDetails
group by OrderIdOfDetail
) as od
on o.OrderId = od.OrderIdOfDetail
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query results:
+---------+---------------------+-------------+---------+
| orderID | orderDate | OrderUserId | Status |
+---------+---------------------+-------------+---------+
| 10 | 01.01.2010 00:00:00 | 1 | Pending |
| 20 | 05.05.2011 00:00:00 | 2 | Pending |
+---------+---------------------+-------------+---------+
subquery only results:
+-----------------+-------------+---------+---------+---------+
| OrderIdOfDetail | DetailCount | Status0 | Status1 | Status2 |
+-----------------+-------------+---------+---------+---------+
| 10 | 5 | 1 | 2 | 2 |
| 20 | 3 | 1 | 1 | 1 |
+-----------------+-------------+---------+---------+---------+

Answer 3

select *, case when DetailStatusID = '1' then 'Pending'
when DetailStatusID = '2' then 'Open'
when DetailStatusID = '0' then 'Closed'
end as OrderStatusDescription
From OrderDetails
Where OrderIdOfDetail = '10'