Selecting count with other columns through joined tables (Oracle SQL) - sql

Question

I have the following query that returns the number of orders a stock item has had:
select count(Orders.OrderID) from Stocks, Orders
where Stocks.StockID = Orders.StockID(+) group by Stocks.StockID;
This returns:
count(Orders.OrderID)
---------------------
0
1
2
0
1
...
However, I also want to display the name of the particular stock item alongside this query. So far, I have tried this, but the following error occurs...
select Stocks.Name, count(Orders.OrderID) from Stocks, Orders
where Stocks.StockID = Orders.StockID(+) group by Stocks.StockID;
The following error occurs:
select Stocks.Name, count(Orders.OrderID) from Stocks, Orders
*
Error: not a GROUP BY expression.
This should return:
Name count(Orders.OrderID)
---------- ---------------------
Item1 0
Item2 1
Item3 2
Item4 0
Item5 1
..... ...
Can anyone help? Thanks in advance.

Answer 1

It should be sth like:
select Stocks.StockID,Stocks.Name, count(Orders.OrderID)
from Stocks
left join Orders
on Stocks.StockID = Orders.StockID -- explicit outer join syntax
group by Stocks.StockID,Stocks.Name; -- matching with select column list

Answer 2

I suggest that you use the COUNT analytic function:
SELECT DISTINCT s.NAME,
COUNT(*) OVER (PARTITION BY s.STOCKID ORDER BY s.STOCKID) AS ON_ORDER
FROM STOCKS s
LEFT OUTER JOIN ORDERS o
ON s.STOCKID = o.STOCKID
dbfiddle here

Answer 3

Another option would be the following;
SELECT S.StockID, S.Name, Orders.[Count]
FROM Stocks AS S
CROSS APPLY
( SELECT COUNT(*) AS [Count]
FROM Orders AS O
WHERE S.StockID = O.StockID
) AS Orders
:)

Answer 4

From your description, it seems that you want to report one aggregate row for each stock name, or in other words group by the stock name:
select s.name as stock_name, count(o.orderid) as orders
from stocks s
left join orders o
on o.stockid = s.stockid
group by s.name;
That will give results like
STOCK_NAME ORDERS
----------- ------
X 123
Y 45
Z 6
You can include other columns from Stocks such as the Stock ID if you want:
select s.stockid, s.name as stock_name, count(o.orderid) as orders
from stocks s
left join orders o
on o.stockid = s.stockid
group by s.stockid, s.name;
which will give results like
STOCKID STOCK_NAME ORDERS
-------- ----------- ------
1 X 123
2 Y 45
3 Z 6