db2中的字符串查找定位函数是locate，可以通过locate函数来分隔字符串，实现字符串的分隔功能。以下给两个Sql供参考：

--用“zz”分隔字符串：

select docname,length(docname) as 长度,locate('zz',docname) as zz的位置,substr(docname,1,locate('zz',docname)-1) as zz之前的字符
 ,substr(docname,  locate('zz',docname),  (length(docname)-locate('zz',docname)+1)) as zz之后的字符

from bd_defdoc where locate('zz',docname)>0

--只截取“zz”之前的字符：
update bd_defdoc set docname=substr(docname,1,locate('zz',docname)-1) where locate('zz',docname)>0