这只是条件聚合:

select pn, sum(loc = 'a') as a, sum(loc = 'b') as b
from table1
group by pn;

如果您有loc值的未知列表，则可能需要动态查询. Google"MySQL动态枢纽".

If you have an unknown list of loc values, then you might need a dynamic query. Google "MySQL dynamic pivot".