Oracle SQL根据另一个表但根据日期更新列

Question

Learning SQL so please forgive me.

I have a table that holds many accounts(and sub accounts) and another table that holds many orders they are custom tables taken from different databases.

What I am trying to do is update order_amt on the account table with the order_val value from the orders table but if there are more than one order with that account I want the order amount from the earliest order date only.

Account Table

Acc _Num..........Comp_Name.......Order_Amt.......Int_Id  
123456789-1.....ABC Ltd.......................................123456789  
123456789-2.....ABC Ltd.......................................123456789  
987654321-1.....Xyz Ltd.........................................987654321       
987654321-2.....Xyz Ltd.........................................987654321  

Orders Table

Order_Num.....Order_Dt.....Order_Val.....Acc_num  
1......................01/01/13......£20.00...........123456789    
2......................01/01/14......£10.00...........123456789  
3......................01/01/10......£100.00..........987654321  
4......................01/01/11......£200.00..........987654321  

So the order_amt for accounts 123456789-1 & 2 = £20.00 and from 987654321-1 & 2 would be £100.00.

UPDATE accounts a  
SET a.order_amt =  
(  
 SELECT order_val  
 FROM orders o  
 WHERE a.int_id = o.acc_num  
 AND EXISTS  
(  
 SELECT MIN(order_dt)  
 FROM orders oa  
 WHERE o.order_num = oa.order_num  
);

I am getting a few errors including the error that more than one row returned? Could anyone please help me?

kind Regards

Eden

Answer 1

I think you need something like this:

UPDATE accounts a  
SET a.order_amt =  
(  
 SELECT order_val  
 FROM orders o  
 WHERE a.int_id = o.acc_num  
 GROUP BY order_val
 HAVING order_dt = MIN(order_dt);
);

Answer 2

Create a FK on the column account_number inside of the orders table and have it reference the auto-increment account id of the accounts table.

Then as Roger suggest, with the slight modification of the column int_id AND a modification of the HAVING clause

UPDATE accounts a 
SET a.order_amount = 
(
    SELECT order_value
    FROM orders o 
    WHERE a.account_number = o.account_number

    GROUP BY order_value
    HAVING MIN(order_date)
)

This will not fix the error that is occurring with more than one row being returned though since there are multiple orders with the same account id attached to them. You will need to be more specific about how what you are needing. Do you want the average of all order amounts to equal the order value in the accounts table? Or maybe the MAX/MIN value?