Mysql 如何使用多案例语句优化查询

我有一个查询，返回一个4列的表，其中显示了购买的数量和购买类型的子类别。问题是，由于它非常慢，我是否可以降低复杂性以提高精化的速度

select
db.start as dateb,
sum(case when(select 
case when  db.preacq = db2.last  and cl.prod_status_id in (1, 2, 3, 4) then dba.buy_datetime
else null end as buy_date
from (
select * from dbda.prod_app
) as db3 
left join (select prod_id, max(preacq) as last from  dbda.prod_app where dbda.prod_app.type = 1
group by 1 ) as db2 on db2.prod_id = db3.prod_id
order by db.preacq  desc limit 1 ) is not null then 1 else 0 end) as prod_bought ,


sum(case when(select 
case when  db.preacq = db2.last  and cl.prod_status_id in (1, 2, 3, 4) and date(db2.last)=
date(dba.buy_datetime) then dba.buy_datetime else null end as buy_date
from (
select * from dbda.prod_app
) as db3 
left join (select prod_id, max(preacq) as last from  dbda.prod_app where dbda.prod_app.type = 1
group by 1 ) as db2 on db2.prod_id = db3.prod_id
order by db.preacq  desc limit 1 ) is not null then 1 else 0 end) as prod_bought_1 , 

sum(case when(select 
case when  db.preacq = db2.last  and cl.prod_status_id in (1, 2, 3, 4) and db2.last <
dba.buy_deal_datetime and date(dba.buy_deal_datetime) < date(dba.buy_datetime) then
dba.buy_datetime else null end as buy_date
from (
select * from dbda.prod_app
) as db3 
left join (select prod_id, max(preacq) as last from  dbda.prod_app where dbda.prod_app.type = 1
group by 1 ) as db2 on db2.prod_id = db3.prod_id
order by db.preacq  desc limit 1 ) is not null then 1 else 0 end) as prod_bought_2 , 

sum(case when(select 
case when  db.preacq = db2.last  and cl.prod_status_id in (1, 2, 3, 4) and date(db2.last) <
date(dba.buy_datetime) and dba.buy_deal_datetime is null then dba.buy_datetime else null end as
buy_date
from (
select * from dbda.prod_app
) as db3 
left join (select prod_id, max(preacq) as last from  dbda.prod_app where dbda.prod_app.type = 1
group by 1 ) as db2 on db2.prod_id = db3.prod_id
order by db.preacq  desc limit 1 ) is not null then 1 else 0 end) as prod_bought_3

from dbda.prod_prod as cl
left join dbda.prod_app as db on cl.id = db.prod_id
left join dbda.prod_acq as dba  on cl.id = dba.id
group by 1

结果如下表所示

+------------+-------------+---------------+---------------+--------------+ | dateb | prod_bought | prod_bought_1 | prod_bought_2 | prod_bought_3| +------------+-------------+---------------+---------------+--------------+ | 11-11-2020 |100 | 50 | 0 | 50 | | 22-11-2020 |200 | 100 | 100 | 0 | | 23-11-2020 |300 | 200 | 50 | 50 | | 24-11-2020 |400 | 200 | 100 | 100 | +------------+-------------+---------------+---------------+--------------+

---

此查询不创建表，它只是返回一个行集，该行集在客户端界面中看起来像一个表。请发布任务本身：源表创建表脚本可能会简化-没有不必要的列和索引，一些示例数据（如插入到脚本中）以及此数据的所需输出（带有逻辑解释）。并指定精确的MySQL版本。