//插入
        public bool InsertClassInfo(ClassInfoData data)
        {
            string sql = "insert into classinfo(classid,specialtyid,"
                         + "studentnumber,remark) values('"
                         + data.Classid + "','" + data.Specialtyid + "','" + data.Studentnumber + "','"
                         + data.Remark + "')";
            DataAccess da = new DataAccess();

            return(da.ExecuteSQL(sql));
        }
        //修改
        public bool UpdateClass(ClassInfoData data)
        {
            string sql = "update classinfo set classid='"
                         + data.Classid + "',Specialtyid='" + data.Specialtyid
                         + "',studentnumber='" + data.Studentnumber
                         + "',remark='" + data.Remark + "'"
                         + " where Classid='" + data.Classid + "'";
            DataAccess da = new DataAccess();

            return(da.ExecuteSQL(sql));
        }
        //查询
        public System.Data.DataSet GetClassInfo(ClassInfoData data)
        {
            string sql = "select * from classinfo where 1=1";
            string s   = "";

            if (data.Classid != "" && data.Classid != null)
            {
                s += " and classid ='" + data.Classid + "'";
            }
            if (data.Specialtyid != "" && data.Specialtyid != null)
            {
                s += " and specialtyid='" + data.Specialtyid + "'";
            }
            sql += s;
            DataAccess da = new DataAccess();

            return(da.GetDataSet(sql, "classinfo"));
        }