Question

I am trying to do an SQL query to get the average spend for a specific customer.

I have written the following SQL (this is slighlty cut down for this example)..

SELECT SUM(price) as sumPrice, COUNT(transactionId) as transactionCount, customerName
FROM customers, transactions
WHERE customers.customerId = transactions.customerId
AND transactiontypeId = 1
GROUP BY customers.customerId

This gives me the sum of the transaction and the count. With this I can then divide the sum by the count to get the average spend. However I would like to be able to get the Average as a value straight out of the database rather than manipulate the data once I have got it out.

Is there any way to do this? I have played around with writing a select within a select but haven;t had much luck as of yet, hence asking on here.

Thanks in advance

Answer 1

MySQL has a mean average function built-in.

SELECT AVG(price) AS averageSpend, customerName
FROM customers, transactions
WHERE customers.customerId = transactions.customerId
AND transactiontypeId = 1
GROUP BY customers.customerId