for update會(huì)鎖表，所以再次執(zhí)行會(huì)導(dǎo)致卡死，解決方案如下

//查看鎖表進(jìn)程
select object_name,machine,s.sid,s.serial# 
from v$locked_object l,dba_objects o ,v$session s
where l.object_id　=　o.object_id and l.session_id=s.sid;

//kill掉進(jìn)程，其中sid,serial#替換為查詢出的結(jié)果
alter system kill session 'sid,serial#'; 

建議執(zhí)行for update nowait，如果鎖表會(huì)立即返回錯(cuò)誤