You can use a previously created alias in the GROUP BY or HAVING statement but not in a SELECT or WHERE statement. This is because the program processes all of the SELECT statement at the same time and doesn’t know the alias’ value yet. The solution is to encapsulate the query in a subquery and … Read more
You need to wrap the SELECT statement into a derived table in order to be able to access the column alias: select cost1, quantity_1, cost_2, quantity_2 total_1 + total_2 as total_3 from ( select cost_1, quantity_1, cost_2, quantity_2, (cost_1 * quantity_1) as total_1, (cost_2 * quantity_2) as total_2 from data ) t There won’t be … Read more
I struggled on the same issue and “mysql syntax is non-standard” is not a valid argument in my opinion. PostgreSQL adds handy non-standard extensions as well, for example “INSERT … RETURNING …” to get auto ids after inserts. Also, repeating large queries is not an elegant solution. However, I found the WITH statement very helpful … Read more