SQLjoin语法案例Data:order.txtorder011,u001,300order012,u002,200order023,u006,100order056,u007,300order066,u003,500order055,u004,300order021,u005,300order014,u001,100order025,u005,300order046,u007,30order067,u003,340order098,u008,310user.txtu001,hls,22,fengjieu002,wangwu,31,lisiu003,zhangyanru,22,tananpe