Question

I’m trying to update sales totals in one table using the existing value plus a sum of values from another table. Here’s a simplified version of the query I’m using:

UPDATE sales_summary 
INNER JOIN sales ON sales_summary.StoreID = sales.StoreID 
SET sales_summary.total = (sales_summary.total + SUM(sales.amount)) 
WHERE PurchaseDate BETWEEN '2011-01-01' AND '2011-01-31' 
GROUP BY sales_summary.StoreID

Can I not use aggregate functions in an UPDATE?

Answer 1

UPDATE sales_summary
INNER JOIN
    (SELECT StoreID, SUM(amount) as amount
     FROM sales
     GROUP BY StoreID) as sales
ON sales_summary.StoreID = sales.StoreID
SET sales_summary.total = sales_summary.total + sales.amount
WHERE PurchaseDate BETWEEN '2011-01-01' AND '2011-01-31'