MySQL SQL初级优化的具体方案；

select company.* from cu_role_extend_company company where 1=1 and company.role_id in(select role.id from cu_role role where 1=1 and role.id in(select relation.role_id from cu_role_relation relation where 1=1 and relation.parent_role_id = (select role.id from cu_role role where 1=1 and role.concerned_id = ( select unionT.id from cu_concerned_union unionT where unionT.id = (select inst.concerned_id from cu_extend_inst inst where 1=1 and inst.inst_code = 'XJ')))));

传统where子查询情况下=>SQL运行下来需要0.666s；查询出来50+数据；筛选数据总量大概在400左右（所有表的数据总量）；

SELECT
companyW.id, companyW.tnt_inst_id, companyW.role_id, companyW.name, companyW.merchant_code,
companyW.person_source,
companyW.settlement_cycle, companyW.settlement_type,
companyW.operation_scope,
companyW.creator_id, companyW.create_time, companyW.modifier_id, companyW.modify_time,companyW.max_amt_set,
companyW.min_amt_set,companyW.notify_url,companyW.latitude,companyW.longitude,companyW.settl_cycle_ctrl,companyW.org_code,
companyW.exn,companyW.exn1,companyW.exn2
FROM
cu_role_extend_company companyW
INNER JOIN (
SELECT DISTINCT
( company.id )
FROM
cu_role_extend_company company
INNER JOIN (
SELECT
role.id
FROM
cu_role role
INNER JOIN (
SELECT
relation.role_id
FROM
cu_role_relation relation
INNER JOIN (
SELECT
role.id
FROM
cu_role role
INNER JOIN (
SELECT
unionT.id
FROM
cu_concerned_union unionT
LEFT JOIN cu_extend_inst inst ON unionT.id = inst.concerned_id
WHERE
1 = 1
AND inst.inst_code = 'XJ'
) x ON role.concerned_id = x.id
) z ON relation.parent_role_id = z.id
) c ON role.id = c.role_id
) v ON company.role_id = v.id
) b ON companyW.id = b.id;

inner join 单字段写全部 情况下，SQL的运行稳定在0.610s左右；

SELECT
*
FROM
cu_role_extend_company companyW
INNER JOIN (
SELECT DISTINCT
( company.id )
FROM
cu_role_extend_company company
INNER JOIN (
SELECT
role.id
FROM
cu_role role
INNER JOIN (
SELECT
relation.role_id
FROM
cu_role_relation relation
INNER JOIN (
SELECT
role.id
FROM
cu_role role
INNER JOIN (
SELECT
unionT.id
FROM
cu_concerned_union unionT
LEFT JOIN cu_extend_inst inst ON unionT.id = inst.concerned_id
WHERE
1 = 1
AND inst.inst_code = 'XJ'
) x ON role.concerned_id = x.id
) z ON relation.parent_role_id = z.id
) c ON role.id = c.role_id
) v ON company.role_id = v.id
) b ON companyW.id = b.id;

inner join 用*查全量字段情况下，SQL的运行稳定在0.460s左右；