How can I utilize the SQL sum function to aggregate values from multiple MySQL tables based on their Primary Keys?

Data and Databases
1 
I have five MySQL tables that contain records for students, each with consistent column names including <em>StudentID</em>, <em>Score1</em>, <em>Score2</em>, <em>Score3</em>, and <em>Overall_Score</em>. The tables are labeled <strong>Semester1</strong>, <strong>Semester2</strong>, <strong>Semester3</strong>, <strong>Semester4</strong>, and <strong>Aggregate</strong>.</p>
<p>My goal is to ensure that when I input scores into the <strong>Semester1</strong>, <strong>Semester2</strong>, <strong>Semester3</strong>, and <strong>Semester4</strong> tables, the total scores for each subject and the overall score are automatically calculated and updated in the <strong>Aggregate</strong> table. I currently have the following code to update the <strong>Aggregate</strong> table after inserting scores into <strong>Semester1</strong>. However, it is only summing the <em>Overall_Score</em> and I want to instead add the <em>Overall_Score</em> from <strong>Semester1</strong> to the existing value in the <strong>Aggregate</strong> table. How can I modify my code to achieve this?

```sql
SELECT SUM( Overall_Score ) 
FROM (
	SELECT SUM( Overall_Score ) AS Overall_Score
	FROM Semester1
	UNION ALL 
	SELECT SUM( Overall_Score ) AS Overall_Score
	FROM Aggregate
) AS Result;
2

hey, I wonder if using UNION ALL alongside subqueries for each semester would help. Have you tried running subqueries from each Semester table and then aggregatin’ them by joining with the Aggregate table? This way you could get total scores per StudentID. Curious to know your approach.

3

You might want to use a JOIN operation. By joining the Aggregate table with Semester1, 2, 3, and 4 on StudentID, you can calculate totals using the SUM function. Then update Aggregate with these calculated sums. This should give you the aggregate score for all semesters.

4

Have you thought about using triggers to automatically update scores in the Aggregate table? By setting up a trigger after each insert or update in your semester tables, you could automate the summation process. What are ur thoughts on automating this using triggers?

5

To efficiently manage the aggregation, consider using a stored procedure which can take care of summing scores from all semesters and updating the Aggregate table accordingly. This approach grants you flexibility, as you can call the procedure whenever necessary, such as after inserting or updating student scores. A stored procedure can contain logic to check for existing records and accordingly update the data, ensuring that the Aggregate table always maintains the most current totals derived from all semester tables.

6

you could also use GROUP BY with a subquery to sum scores from each semester table. Then combine & update the Aggregate table. It’s a bit similar to joins. This way once you select each student’s accumulated score, they can be smoothly added for the overall calculation. just another option.