MySQL - Error Code 1630 "FUNCTION does not exist."

Question

`

SELECT month(orderdate), category , sales * 100 / total_sales as pct_total_sales
FROM
(
    SELECT a.month(orderdate), a.category, a.sales, sum(b.sales) as total_sales
    FROM superstore a
    JOIN superstore b on a.month(orderdate) = b.month(orderdate)
        and b.category in ('technology', 'furniture')
        WHERE a.category in ('technology', 'furniture')
GROUP BY 1,2,3
) aa

`

"Error Code: 1630. FUNCTION a.month does not exist."

Trying to self-jjoin, MySQL assumes "a.month()" as a funcion. How can I fix this error?

Answer 1

If you want to express the month (orderdate) in the subquery, you need to define an alias in the subquery, otherwise it will cause ambiguous definitions. There are a few issues with the provided SQL query: SELECT month(orderdate) as month , category, sales * 100 / total_sales as pct_total_sales FROM ( SELECT a.month(orderdate) , a.category, a.sales, sum(b.sales) as total_sales FROM superstore a JOIN superstore b on MONTH(a.orderdate) = Month(b.orderdate) and b.category in ('technology', 'furniture') WHERE a.category in ('technology', 'furniture') GROUP BY 1,2,3 ) aa