You have a table Orders with columns CustomerID, OrderAmount. How do you write a query to find the total order amount for each customer?

hard📝 Application Q15 of 15

SQL - Aggregate Functions

You have a table Orders with columns CustomerID, OrderAmount. How do you write a query to find the total order amount for each customer?

ASELECT SUM(OrderAmount) FROM Orders GROUP BY CustomerID;

BSELECT CustomerID, SUM(OrderAmount) FROM Orders;

CSELECT CustomerID, TOTAL(OrderAmount) FROM Orders GROUP BY CustomerID;

DSELECT CustomerID, SUM(OrderAmount) FROM Orders GROUP BY CustomerID;

Step-by-Step Solution

Solution:

Step 1: Use GROUP BY to group rows by CustomerID
This groups all orders per customer so we can sum their amounts.
Step 2: Use SUM(OrderAmount) to add orders per group
SUM() calculates total order amount for each customer group.
Final Answer:
SELECT CustomerID, SUM(OrderAmount) FROM Orders GROUP BY CustomerID; -> Option D
Quick Check:
GROUP BY + SUM() = total per group [OK]

Quick Trick: Use GROUP BY with SUM() to total per group [OK]

Common Mistakes:

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