根据时间进行累加

group by

For the table QA, the query about the accumulation of the count of questions should be:

Table: QA

Date          Count

Feb              10

March          20

April             30

select q1.date, sum(q2.count) as acm

from QA q1, QA q2

where q1.date <= q2.date

group by q1.date

order by q1.date;