sql优化：
帮忙优化一下sql，现在的sql跑不出来数据。
sql如下：
select
count(distinct `jl`.`guid`) as `f30`,
round(sum(`jl`.`jzzmj`),2) as `f31`,
`jl`.`zcssdw` as `zcssdw`
from
(
(
`mall_personnel_org_db`.`t_fcxt_tdgl` `td`
left join (
select
distinct `td_1`.`guid` as `guid`,
`td_1`.`tdzmj` as `tdzmj`,
`td_1`.`zcssdw` as `zcssdw`
from
(((`mall_personnel_org_db`.`t_fcxt_yw_tdzgx` `gx`
left join `mall_personnel_org_db`.`t_fcxt_tdzgl` `tdz` on
((`gx`.`tdz_guid` = `tdz`.`guid`)))
left join `mall_personnel_org_db`.`t_fcxt_tdgl` `td_1` on
((`gx`.`td_guid` = `td_1`.`guid`)))
left join `mall_personnel_org_db`.`t_fcxt_jzgl` `jz` on
((`jz`.`guid` = `td_1`.`sjjzguid`)))
where
((`jz`.`ztdm` = '0')
and (`gx`.`ztdm` = '0')
and (`tdz`.`ztdm` = '0')
and (`td_1`.`ztdm` = '0')
and (`td_1`.`qszt` = '3301')
and (`td_1`.`sjjzguid` is not null)
and (`td_1`.`sjjzguid` <> ''))) `a` on
((`a`.`guid` = `td`.`guid`))
)
left join `mall_personnel_org_db`.`t_fcxt_jl` `jl` on
((`jl`.`sjtdguid` = `td`.`guid`))
)
where
((`td`.`ztdm` = '0')
and (`jl`.`ztdm` = '0')
and (`jl`.`qszt` = '3301')
and isnull(`a`.`guid`))
group by
jl.zcssdw
感觉有点乱啊，你可以分布执行，看到哪一步出现问题了