text字段为空查询

SELECT     TOP (200) bh, factory, cargo, clientcargo, bedcolor, bedsize, category, opdate, finished, outboxnumber, outanumber, outunit, excode, ifdapei,
                      tradecompany, needlemachine, needle1, needle2, bz, jzdapei, otherbnumber, washbnumber, jpremainder, remainder, nbnumber, classnumber,
                      opcontent, jianpin, nanumber, confirmdate, opconfirm
FROM         outbh
WHERE     (DATALENGTH(bz) <> 0)