sql - I'm trying to Calculate the amount to be charged for each assignment. Using Oracle DBMS

Question

I have this so far but stuck.....

SELECT a.Total_Assignment_Hrs, a.Assignment_Cost_Per_Day
SUM (Total_Assignment_Hrs-Assignment_Cost_Per_Day) AS Assignment_Cost
FROM Projects p,Employee_Records e, Assignments a
WHERE p.ProjectID=a.ProjectID
GROUP BY a.AssignmentID, a.Assignment_Name;

The issue i'm having is that i need to calculate the top SUM but i can't get it to produce a result with the sum statement in how do extend it to show what i need ?.

Answer 1

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At the minute i can only get to here but need to calculate the total assignment hrs and assignment cost per day as a total