remove connection.release when sql has error
remove connection.release when sql has error

akira-cn/thinkjs,Qihoo360/thinkjs,75team/thinkjs,maxzhang/thinkjs,75team/thinkjs,thinkjs/thinkjs,maxzhang/thinkjs,akira-cn/thinkjs,maxzhang/thinkjs,75team/thinkjs,akira-cn/thinkjs,snadn/thinkjs