您可以在MysqL中使用变量（或非常复杂的相关子查询）来执行此操作。在其他数据库中，您将使用窗口/分析功能。
逻辑是：
select person, count(*) as numMonths
from (select person, ym, @ym, @person,
if(@person = person and @ym = ym - 1, @grp, @grp := @grp + 1) as grp,
@person := person,
@ym := ym
from (select distinct person, year(purdate)*12+month(purdate) as ym
from records r
) r cross join
(select @person := '', @ym := 0, @grp := 0) const
order by 1, 2
) pym
group by person, grp;
602392714
清零编程群