Let’s take a look at an example to understand how to use the SELECT statement with an aggregate function and the HAVING clause.

Suppose we have a table called Orders with the following columns:

• OrderID (primary key)
• CustomerID
• OrderAmount

Now, let’s say we want to find the customers who have placed orders with a total amount greater than $1000.

Here’s how we can achieve this using the SELECT, SUM, and HAVING clauses in SQL:

SELECT CustomerID, SUM(OrderAmount) AS TotalAmount
FROM Orders
GROUP BY CustomerID
HAVING SUM(OrderAmount) > 1000;

In the above example, we first select the CustomerID and calculate the sum of OrderAmount for each customer using the SUM function. We also give this calculated sum a column alias TotalAmount.

Next, we group the result by CustomerID using the GROUP BY clause. This ensures that the aggregate function operates on each group separately.

Finally, we use the HAVING clause to filter the results based on the condition that the sum of OrderAmount should be greater than 1000.

By executing this query, we will retrieve the CustomerID and the total order amount for customers who have placed orders with a sum greater than $1000.

Remember, the HAVING clause is used specifically for filtering based on aggregate functions, while the WHERE clause is used for applying conditions to individual rows of data.

#SQL #AggregateFunctions