How to use Sum and Inner Join in a delete statement

Question

I have a table called TableName which I want to delete from all rows that SUM of their product quantity is less than 2. I need to inner join table oc_order_product and SUM the values having the same product_id then use this SUM value in where clause to delete all rows with SUM less than 2. I am using the following query right now:

  Delete TablenName from TablenName
        INNER JOIN oc_order_product 
                     ON oc_order_product.product_id = TablenName.product_id
   where oc_order_product.quantity HAVING SUM(oc_order_product.quantity) < 2;

Which I am getting the following error:

    #1064 - You have an error in your SQL syntax; check the manual that
 corresponds to your MariaDB server version for the right syntax 
to use near 'HAVING SUM(oc_order_product.quantity) < 2' at line 4

Answer 1

Hmmm . . . If you need to do aggregation, you need to do it before the join :

Delete t
    from TablenName t join
         (select op.product_id, sum(op.quantity) as sumquantity
          from oc_order_product op
          group by op.product_id
         ) op
         on op.product_id = t.product_id and op.sumquantity < 2;