select course as '成绩总和',
sum(case when class = 'JSD1701' then score else 0 end) as 'jsd1701',
sum(case when class = 'JSD1702' then score else 0 end) as 'jsd1702',
sum(case when class = 'JSD1703' then score else 0 end) as 'jsd1703',
sum(case when class = 'JSD1704' then score else 0 end) as 'jsd1704'
from class_score_sum group by course;