写了一个稍微复杂点的sql心得

select pcode from (
        select h.k,h.d,h.m,h.u,l.areacode,
               l.areacode||substr(h.u,4,length(h.u))||h.k pcode
         from(
        select j.k,j.d,j.m,j.u from(
        select lpad(f,3,0) as k,d, m,u from(
        select xx.areacode d,nvl(count(cy.pcode),'001')f,mx.m,mx.shopcode u
        from cz_s_jtxx xx, cz_s_jtcy cy , 
          ( select a.m,d.shopid,d.shopcode from
        (select shopid m,parentid from s_shop where shoptype=1) a,
        (select shopid,parentid from s_shop where shoptype=2) b,
        (select shopid,parentid from s_shop where shoptype=3)c,
        (select shopid,parentid,shopcode from s_shop where shoptype=4)d
        where d.parentid=c.shopid
        and c.parentid=b.shopid
        and b.parentid=a.m
        and d.shopid=14725) mx
        where xx.pcode = cy.pcode
        and xx.areacode=mx.shopid
        group by xx.areacode,mx.m,mx.shopcode))j)h, 
        (select areacode,shopid  from cz_s_area) l 
       where h.m=l.shopid)
首先 从最里层的 sql说起：
select a.m,d.shopid,d.shopcode from
        (select shopid m,parentid from s_shop where shoptype=1) a,