Gridview的操作（3）

<div>
    <a href="test.aspx?id=add" style="text-decoration:none">增加一个用户</a>
        <asp:GridView ID="gridview1" runat="server" AutoGenerateColumns="false">
            <Columns>
            <asp:BoundField DataField ="CustomerID" HeaderText ="姓名" />
            <asp:BoundField DataField ="CompanyName" HeaderText ="公司名称" />
            <asp:BoundField DataField ="ContactName" HeaderText ="联系人" />
            <asp:BoundField DataField ="ContactTitle" HeaderText ="职务" />
            <asp:TemplateField HeaderText ="修改">
            <ItemTemplate>
            <a href="test.aspx?id=edit&userid=<%#Eval("CustomerID") %>"><%#Eval("City") %></a>
            </ItemTemplate>
            </asp:TemplateField>
            </Columns>
        </asp:GridView>
    </div>

后台代码：

 protected void Page_Load(object sender, EventArgs e)
    {
        if (Request.QueryString["id"] == null)
        {
            Page.RegisterStartupScript("", "<script language=javascript>alert('登陆错误!');location='Default.aspx'</script>");
        }
        else
        {
            if (Request.QueryString["id"] == "edit")
            {

                if (!IsPostBack)
                {
                    databind();
                }
            }
            else
            {
                this.TextBox1.ReadOnly = false;
                if (!IsPostBack)
                {
                    this.TextBox2.Enabled = false;
                    this.TextBox3.Enabled = false;
                    this.TextBox4.Enabled = false;
                     
                } 
            }
        }

    }
    public void databind()
    {
        SqlConnection con = new SqlConnection(@"Data Source=.\SQLEXPRESS;Initial Catalog=Northwind;Integrated Security=True");
        SqlCommand cmd = new SqlCommand("Select * From Customers where CustomerID =@CustomerID", con);
        SqlParameter sp = new SqlParameter("@CustomerID", SqlDbType.NChar, 5);
        sp.Value = Request.QueryString["userid"].ToString();
        cmd.Parameters.Add(sp);
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        DataSet ds = new DataSet();
        da.Fill(ds);
        this.TextBox1.Text = Request.QueryString["userid"];
        this.TextBox2.Text = ds.Tables[0].Rows[0]["CompanyName"].ToString();
        this.TextBox3.Text = ds.Tables[0].Rows[0]["ContactName"].ToString();
        this.TextBox4.Text = ds.Tables[0].Rows[0]["ContactTitle"].ToString();
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        SqlConnection con = new SqlConnection(@"Data Source=.\SQLEXPRESS;Initial Catalog=Northwind;Integrated Security=True");
        if (Request.QueryString["id"] == "edit")
        {
            SqlCommand cmd = new SqlCommand("Update Customers set CompanyName=@CompanyName,ContactName=@ContactName,ContactTitle=@ContactTitle where CustomerID =@CustomerID", con);
            SqlParameter[] sp = new SqlParameter[4];

            sp[0] = new SqlParameter("@CompanyName", SqlDbType.NVarChar, 40);
            sp[1] = new SqlParameter("@ContactName", SqlDbType.NVarChar, 30);
            sp[2] = new SqlParameter("@ContactTitle", SqlDbType.NVarChar, 30);
            sp[3] = new SqlParameter("@CustomerID", SqlDbType.NChar, 5);
            sp[0].Value = this.TextBox2.Text.Trim();
            sp[1].Value = this.TextBox3.Text.Trim();
            sp[2].Value = this.TextBox4.Text.Trim();
            sp[3].Value = this.TextBox1.Text.Trim();
            cmd.Parameters.AddRange(sp);
            if (con.State == ConnectionState.Closed)
            {
                con.Open();
            }
            cmd.ExecuteNonQuery();
            con.Close();
            Page.RegisterStartupScript("", "<script language=javascript>alert('修改成功!');location='Default.aspx'</script>");
        }
        else if (Request.QueryString["id"] == "add")
        {
            
            SqlCommand cmd = new SqlCommand();
            cmd.Connection = con;
            cmd.CommandText = "Insert into Customers(CustomerID,CompanyName,ContactName,ContactTitle) values(@CustomerID,@CompanyName,@ContactName,@ContactTitle)";
            SqlParameter[] sp = new SqlParameter[4];
            sp[0] = new SqlParameter("@CustomerID",SqlDbType.NChar,5);
            sp[1] = new SqlParameter("@CompanyName",SqlDbType.NVarChar,40);
            sp[2] = new SqlParameter("@ContactName",SqlDbType.NVarChar,30);
            sp[3] = new SqlParameter("@ContactTitle",SqlDbType.NVarChar,30);
            sp[0].Value = this.TextBox1.Text.Trim();
            sp[1].Value = this.TextBox2.Text.Trim();
            sp[2].Value = this.TextBox3.Text.Trim();
            sp[3].Value = this.TextBox4.Text.Trim();
            cmd.Parameters.AddRange(sp);
            if (con.State == ConnectionState.Closed)
            {
                con.Open();
            }
            cmd.ExecuteNonQuery();
            con.Close();
            Page.RegisterStartupScript("", "<script language=javascript>alert('修改成功!');location='Default.aspx'</script>");
        }
    }
    protected void TextBox1_TextChanged(object sender, EventArgs e)
    {
        SqlConnection con = new SqlConnection(@"Data Source=.\SQLEXPRESS;Initial Catalog=Northwind;Integrated Security=True");
        SqlCommand cmd = new SqlCommand("Select * From Customers where CustomerID =@CustomerID", con);
        SqlParameter sp = new SqlParameter("@CustomerID", SqlDbType.NChar, 5);
        sp.Value = this.TextBox1.Text.Trim();
        cmd.Parameters.Add(sp);
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        DataSet ds = new DataSet();
        da.Fill(ds);
        if (ds.Tables[0].Rows.Count > 0)
        {
            this.Label5.Text = "用户名已经存在!";
            this.TextBox2.Enabled = false;
            this.TextBox3.Enabled = false;
            this.TextBox4.Enabled = false;
        }
        else
        {
            this.Label5.Text = "用户名不存在!";
            this.TextBox2.Enabled = true;
            this.TextBox3.Enabled = true;
            this.TextBox4.Enabled = true;
        }
    }