oracle 运行脚本：character set mismatch

(select 
bg.sysyear,
bg.orgontid,
bg.orgname,
bg.accvouchercode,
bg.accvouchername,
'' as accvoucherprop
from gzyt_middle.beginningbalance bg
where bg.ledger = '02' 
and bg.sysyear = '2015')
union all
(select 
ag.sysyear,
ag.orgontid,
ag.orgname,
ag.accvouchercode,
ag.accvouchername,
ag.accvoucherprop
from gzyt_middle.accountingnumber ag
where ag.ledger = '02'
and ag.sysyear = '2014')

报如题错误，郁闷很久都无法解决问题，正如摘要中提到的nvarchar2类型的原因

解决方法 ''前面加N 就不会报错了；

问题解决我是参考

http://blog.itpub.net/936/viewspace-60689/