fix add user select bug

dao/dao-user.go

@@ -139,6 +139,10 @@ func InsertUser(user *entity.User, userType string) *result.Result {
 		if err != nil && err != sql.ErrNoRows {
 			return result.UNKNOW_ERROR.SetMsg(err.Error())
 		}
+		// count == examId []
+		if len(count) == 0 {
+			return result.SUCCESS.SetData(id)
+		}
 
 		// 6、添加考试记录
 		sqlStr = "insert into exam_record(create_at, update_at, user_id, exam_id,status) values (?,?,?,?,?)"