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Answer: Aggregate Records Using SUM

Explore how to use the SQL SUM aggregate function to compute total values within a dataset. Understand the application of aliases, filtering with WHERE clauses, and alternative methods like CASE statements to conditionally sum data. This lesson prepares you to apply these techniques confidently in SQL interview problems involving aggregate calculations.

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Solution

The solution is given below:

MySQL
/* The query to find the sum of students' marks in Mathematics */
SELECT SUM(Marks) AS TotalMarksMaths
FROM   StudentGrades
WHERE  Subject = 'Mathematics';

Explanation

The explanation of the solution code is given below:

  • Line 2: The SELECT query finds the sum of students’ marks for Mathematics. We use AS to set an alias for the column.

  • Line 3: The FROM clause specifies the table, StudentGrades.

  • Line 4: In the ...