请注释下一下代码

Question

    public static void BindDG(GridView dg, string id, string strSql, string Tname)
    {
        SqlConnection conn = DBCon();
        SqlDataAdapter sda = new SqlDataAdapter(strSql, conn);
        DataSet ds = new DataSet();
        sda.Fill(ds, Tname);
        dg.DataSource = ds.Tables[Tname];
        dg.DataKeyNames = new string[] { id };
        dg.DataBind();
    }public void gvExaminationInfo_Bind()
    {
        string strsql = "select * from exampaper order by 试卷ID desc";
        BaseClass.BindDG(gvExaminationInfo, "试卷ID", strsql, "SingleChooseInfo");
        SqlConnection conn = BaseClass.DBCon();
        conn.Open();
        SqlCommand cmd = new SqlCommand("select * from exampaper", conn);
        SqlDataReader sdr = cmd.ExecuteReader();
        this.ddlEkm.DataSource = sdr;
        this.ddlEkm.DataTextField = "试卷ID";
        this.ddlEkm.DataValueField = "试卷ID";
        this.ddlEkm.DataBind();
        conn.Close();
    }
    protected void gvExaminationInfo_PageIndexChanging(object sender, GridViewPageEventArgs e)
    {
        gvExaminationInfo.PageIndex = e.NewPageIndex;
        gvExaminationInfo_Bind();
    }
    protected void gvExaminationInfo_RowDeleting(object sender, GridViewDeleteEventArgs e)
    {
        int 试卷ID = (int)gvExaminationInfo.DataKeys[e.RowIndex].Value;//获取GridView主键的值
        string strsql = "delete from exampaper where 试卷ID ='" + 试卷ID + "'";
        BaseClass.OperateData(strsql);
        gvExaminationInfo_Bind();
    }
    protected void btnSerch_Click(object sender, EventArgs e)
    {
        lbltype.Text = ddlEkm.SelectedItem.Text.Trim();
        string strsql = "select * from exampaper where 试卷ID ='" + ddlEkm.SelectedItem.Text.Trim() + "'";
        BaseClass.BindDG(gvExaminationInfo, "试卷ID", strsql, "SingleChooseInfo");
        SqlConnection conn = BaseClass.DBCon();
        conn.Open();
        SqlCommand cmd = new SqlCommand("select * from exampaper", conn);
        SqlDataReader sdr = cmd.ExecuteReader();
        this.ddlEkm.DataSource = sdr;
        this.ddlEkm.DataTextField = "试卷ID";
        this.ddlEkm.DataValueField = "试卷ID";
        this.ddlEkm.DataBind();
        conn.Close();
    }

Answer 1

public static void BindDG(GridView dg, string id, string strSql, string Tname)
    {
        SqlConnection conn = DBCon();定义一个数据库连接
        SqlDataAdapter sda = new SqlDataAdapter(strSql, conn);定义一个数据适配器
        DataSet ds = new DataSet();
        sda.Fill(ds, Tname);执行strsql语句，并把结果把在结果集ds,
        dg.DataSource = ds.Tables[Tname];把结果集绑定到dg
        dg.DataKeyNames = new string[] { id };
        dg.DataBind();
    }public void gvExaminationInfo_Bind()
    {
        string strsql = "select * from exampaper order by 试卷ID desc";
        BaseClass.BindDG(gvExaminationInfo, "试卷ID", strsql, "SingleChooseInfo");
        SqlConnection conn = BaseClass.DBCon();
        conn.Open();
        SqlCommand cmd = new SqlCommand("select * from exampaper", conn);
        SqlDataReader sdr = cmd.ExecuteReader();
        this.ddlEkm.DataSource = sdr;
        this.ddlEkm.DataTextField = "试卷ID";
        this.ddlEkm.DataValueField = "试卷ID";
        this.ddlEkm.DataBind();
        conn.Close();
    }
    protected void gvExaminationInfo_PageIndexChanging(object sender, GridViewPageEventArgs e)
    {
        gvExaminationInfo.PageIndex = e.NewPageIndex; 这个应该是分页控件，翻页时的事件
        gvExaminationInfo_Bind();
    }
    protected void gvExaminationInfo_RowDeleting(object sender, GridViewDeleteEventArgs e)
    {
        int 试卷ID = (int)gvExaminationInfo.DataKeys[e.RowIndex].Value;//获取GridView主键的值
        string strsql = "delete from exampaper where 试卷ID ='" + 试卷ID + "'";
        BaseClass.OperateData(strsql);  ？？执行删除操作
        gvExaminationInfo_Bind();删除后重新绑定，也就是刷新
    }
    protected void btnSerch_Click(object sender, EventArgs e)
    {
        lbltype.Text = ddlEkm.SelectedItem.Text.Trim();
        string strsql = "select * from exampaper where 试卷ID ='" + ddlEkm.SelectedItem.Text.Trim() + "'";
        BaseClass.BindDG(gvExaminationInfo, "试卷ID", strsql, "SingleChooseInfo");
        SqlConnection conn = BaseClass.DBCon();
        conn.Open();打开数据库连接
        SqlCommand cmd = new SqlCommand("select * from exampaper", conn);
        SqlDataReader sdr = cmd.ExecuteReader();执行sql语句
        this.ddlEkm.DataSource = sdr;
        this.ddlEkm.DataTextField = "试卷ID";
        this.ddlEkm.DataValueField = "试卷ID";
        this.ddlEkm.DataBind();
        conn.Close();
    }