fix bug for mysql
fix bug for mysql

wfxiang08/tcpcopy,left2right/tcpcopy,wfxiang08/tcpcopy,ycaihua/tcpcopy,sshling/tcpcopy,u20024804/tcpcopy,u20024804/tcpcopy,ycaihua/tcpcopy,liviusATnetskope/second,horryq/tcpcopy,caosiyang/tcpcopy,horryq/tcpcopy,eliteYang/tcpcopy,caosiyang/tcpcopy,sshling/tcpcopy,liviusATnetskope/second,eliteYang/tcpcopy,daodaoliang/tcpcopy,left2right/tcpcopy,daodaoliang/tcpcopy