sql优化

select orderkey,
       externorderkey,
       type,
       COMPANY,
       ORDERDATE,
       ORDERSTATUS,
       count(sku) countsku,
       sum(WEIGHT) WEIGHT,
       sum(CUBE) CUBE,
       carnum,
       carrierroutestatus
  from (select pk.orderkey,
               o.externorderkey,
               (select description
                  from codelkup
                 where listname = 'ORDERTYPE'
                   and code = o.type) type,
               (select COMPANY
                  from storer
                 where type = '2'
                   and storerkey = o.consigneekey) COMPANY,
               TO_CHAR(O.ORDERDATE, 'YYYY-MM-DD') ORDERDATE,
               (select DESCRIPTION
                  from ORDERSTATUSSETUP
                 where code = O.status) ORDERSTATUS,
               od.SKU,
               SUM(PK.PDUDF3) / 1000 WEIGHT,
               SUM(PK.CUBEUOM) / 1000000 CUBE,
               (select susr5 from orders where orderkey = pk.orderkey) carnum,
               o.carrierroutestatus
          from pickdetail pk, orders o, orderdetail od, sku sku, STORER S
         where pk.orderkey = od.orderkey
           and pk.orderlinenumber = od.orderlinenumber
           and od.orderkey = o.orderkey
           and sku.sku = od.sku
           and sku.storerkey = od.storerkey
           and O.CONSIGNEEKEY = S.STORERKEY
           and S.TYPE = '2' 
          -- and od.orderkey='0000005238'
         group by pk.orderkey,
                  o.externorderkey,
                  o.type,
                  o.consigneekey,
                  TO_CHAR(O.ORDERDATE, 'YYYY-MM-DD'),
                  O.status,
                  od.sku,
                  o.carrierroutestatus)
 group by orderkey,
          externorderkey,
          type,
          COMPANY,
          ORDERDATE,
          ORDERSTATUS,
          carnum,
          carrierroutestatus
          
      order by orderkey desc哪位大神可以帮小弟优化一下sql，查询速度太慢了，搞不出来了