SQL的or及括号

想查询的是借方和贷方金额的。
如果不加括号，查询不仅慢，并且效率低。

select gl_detail.explanation,
       bd_accsubj.dispname,
       gl_detail.debitamount 借方,
       gl_detail.creditamount 贷方,
       gl_detail.prepareddatev 制单日期,
       gl_voucher.no 凭证号,
       wmsys.wm_concat(gl_freevalue.valuecode) valuecode,
       wmsys.wm_concat(gl_freevalue.valuename) valuename
  from bd_accsubj
  join gl_detail
    on gl_detail.pk_accsubj = bd_accsubj.pk_accsubj
  join bd_glorgbook
    on bd_glorgbook.pk_glorgbook = bd_accsubj.pk_glorgbook
  join gl_voucher
    on gl_detail.pk_voucher = gl_voucher.pk_voucher
  left join gl_freevalue
    on gl_detail.assid = gl_freevalue.freevalueid
 where gl_detail.dr = '0'
   and gl_detail.yearv = '2011'
   and bd_glorgbook.glorgbookcode = '0100-0001'
  and   (gl_detail.debitamount='6202549' or gl_detail.creditamount='6202549')
--and bd_accsubj.subjcode like '150103%'
 group by gl_detail.explanation,
          bd_accsubj.dispname,
          gl_detail.creditamount,
          gl_detail.debitamount,
          gl_detail.prepareddatev,
          gl_voucher.no
 order by gl_detail.prepareddatev, gl_voucher.no