提高主细节SQL代码的性能

我有两张桌子

我需要一份报告，包括

Payment1

，

Payment2

列中的姓名和付款金额，不得重复

所以我写下：

(
  SELECT Pid1, SUM(Payment1) as sum1, COUNT(*) as number, _name
  FROM perform, Person
  WHERE perform.Pid1= Person.id
  GROUP BY _name, Pid1
)
UNION
(
  SELECT Pid2, SUM(Payment2) as sum2, COUNT(*) as number, _name 
  FROM perform, Person
  WHERE perform.Pid2= Person.id
  GROUP BY _name, Pid2
)

和输出：

---

这个代码可以工作，但是太慢了。如何提高性能？

通过将

联合

移动到子查询，可以减少加入

个人

的次数：

select  pers.id
,       perf_sum.sum_payment
,       perf_sum.count_payment
,       pers._name
from    (
        select  pid
        ,       count(*) as count_payment
        ,       sum(payment) as sum_payment
        from    (
                select  PID1 as pid
                ,       Payment1 as payment
                from    perform
                union all
                select  PID2
                ,       Payment2
                from    perform
                ) perf
        group by
                pid
        ) perf_sum
join    person pers
on      perf.pid = pers.id