Question

I have a orders table that have order detail and the column named Category where Category is the type of order.

Now the customer can search the order details.

Now what i want to write a query the show the order details and a column called TotalOrder that will show the TotalOrders placed by all customers for that category,

Example Say the Order Table like

OrderID  CustomerID  OrderDetails Category   
1         1           test         A1
2         1           test1        A2
3         2           test3        A2
4         3           test4        A2

So if query for the order id 1

It will result like with Order ID 2

OrderID   Cust_ID     OrderDetails  Category      TotalOrdersInThisCategory
2         1           test          A2            3     

This scenario is a demonstration of the actual problem.

How can i achieve this?

Do i need to fetch the Order detail in one query and Another query with group by Category clause and then make a inner join. Any better ideas is appreciable.

The order details will have few millions of records.

Please Suggest Some Better Title of this question

Any help is appreciated

Answer 1

SELECT 
  OrderID,
  Cust_ID,
  OrderDetails,
  Category,
  (select count(*) from orders where category = o.category) TotalOrdersInThisCategory  
FROM
  Orders o

or you could try this:

SELECT 
  o.OrderID,
  o.Cust_ID,
  o.OrderDetails,
  o.Category,
  c.TotalOrdersInThisCategory  
FROM
  Orders o
INNER JOIN (select category, count(*) from orders group by category) c
        ON o.Category = c.Category