SQL, sum inside of case condition

I’m trying to learn sql query and i want to solve the following problem.

Assume the table as follow:

Select schoolname
SUM(CASE WHEN (grade='1' ) THEN totalA ELSE 0 END) AS t1A,
SUM(CASE WHEN (grade='1' ) THEN totalB ELSE 0 END) AS t1B,
SUM(CASE WHEN (grade='2' ) THEN totalA ELSE 0 END) AS t2A,
SUM(CASE WHEN (grade='2' ) THEN totalB ELSE 0 END) AS t2B,

I would like to know if it is possible to add both totalA and B in one case condition.

I tried

Select schoolname
CASE WHEN (grade='1' ) THEN SUM(totalA+totalB) ELSE 0 END AS Grade 1,
CASE WHEN (grade='2' ) THEN SUM(totalA+totalB) ELSE 0 END AS Grade 2,
From school
Group By schoolname

But it give me error.

I want to achieve the following:

>Solution :

Yes it is possible by group by query of MySQL in the same table.

For that you need to use this type of query:

SELECT schoolname,
    SUM(CASE WHEN (grade = 1) THEN totalA + totalB ELSE 0 END) AS grade_1,
    SUM(CASE WHEN (grade = 2) THEN totalA + totalB ELSE 0 END) AS grade_2
FROM school
GROUP BY schoolname