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前一示例的一個問題是，當行可編輯時，主鍵字段 (au_id) 也呈現(xiàn)為文本輸入框。您不希望客戶端更改該值，因為需要它來確定更新數(shù)據(jù)庫中的哪一行。幸運的是，可以通過精確指定每一列相對于可編輯行的外觀，禁用將此列呈現(xiàn)為文本框。為此需在 DataGrid 的 Columns 集合中定義每一行，使用 BoundColumn 控件分配每一列的數(shù)據(jù)字段。使用此方法，您可以完全控制列的順序，以及它們的 ReadOnly 屬性。對于 au_id 列，將 ReadOnly 屬性設(shè)置為 true。當行處于編輯模式時，此列將繼續(xù)呈現(xiàn)為標簽。下面的示例說明此方法。
aspx文件里面加入DataGrid控件半設(shè)置屬性，代碼如下：
<body MS_POSITIONING="GridLayout">
<form id="form7" method="post" runat="server">
<asp:Literal id="Message" runat="server"></asp:Literal>
<ASP:DataGrid id="DataGrid1" runat="server" Width="800" BackColor="#ccccff" BorderColor="black" ShowFooter="false" CellPadding="3" CellSpacing="0" Font-Name="Verdana" Font-Size="8pt" HeaderStyle-BackColor="#aaaadd" OnEditCommand="MyDataGrid_Edit" OnCancelCommand="MyDataGrid_Cancel" OnUpdateCommand="MyDataGrid_Update" DataKeyField="au_id" AutoGenerateColumns="false">
<Columns>
<asp:EditCommandColumn EditText="編輯" CancelText="取消" UpdateText="更新" ItemStyle-Wrap="false" />
<asp:BoundColumn HeaderText="au_id" SortExpression="au_id" ReadOnly="True" DataField="au_id" ItemStyle-Wrap="false" />
<asp:BoundColumn HeaderText="au_lname" SortExpression="au_lname" DataField="au_lname" />
<asp:BoundColumn HeaderText="au_fname" SortExpression="au_fname" DataField="au_fname" />
<asp:BoundColumn HeaderText="phone" SortExpression="phone" DataField="phone" />
<asp:BoundColumn HeaderText="address" SortExpression="address" DataField="address" />
<asp:BoundColumn HeaderText="city" SortExpression="city" DataField="city" />
<asp:BoundColumn HeaderText="state" SortExpression="state" DataField="state" />
<asp:BoundColumn HeaderText="zip" SortExpression="zip" DataField="zip" />
<asp:BoundColumn HeaderText="contract" SortExpression="contract" DataField="contract" />
</Columns>
</ASP:DataGrid>
</form>
</body>
aspx.cs文件中加入下面代碼：
導(dǎo)入using System.Data.SqlClient;
定義SqlConnection myConnection;
private void Page_Load(object sender, System.EventArgs e)
{
myConnection = new SqlConnection("user id=sa;password=;initial catalog=pubs;data source=jeff");
if (!IsPostBack)
BindGrid();
}
public void MyDataGrid_Edit(Object sender, DataGridCommandEventArgs E)
{
DataGrid1.EditItemIndex = (int)E.Item.ItemIndex;
BindGrid();
}
public void MyDataGrid_Cancel(Object sender, DataGridCommandEventArgs E)
{
DataGrid1.EditItemIndex = -1;
BindGrid();
}
public void MyDataGrid_Update(Object sender, DataGridCommandEventArgs E)
{
String updateCmd = "UPDATE Authors SET au_id = @Id, au_lname = @LName, au_fname = @FName, phone = @Phone, "
+ "address = @Address, city = @City, state = @State, zip = @Zip, contract = @Contract where au_id = @Id";
SqlCommand myCommand = new SqlCommand(updateCmd, myConnection);
myCommand.Parameters.Add(new SqlParameter("@Id", SqlDbType.NVarChar, 11));
myCommand.Parameters.Add(new SqlParameter("@LName", SqlDbType.NVarChar, 40));
myCommand.Parameters.Add(new SqlParameter("@FName", SqlDbType.NVarChar, 20));
myCommand.Parameters.Add(new SqlParameter("@Phone", SqlDbType.NChar, 12));
myCommand.Parameters.Add(new SqlParameter("@Address", SqlDbType.NVarChar, 40));
myCommand.Parameters.Add(new SqlParameter("@City", SqlDbType.NVarChar, 20));
myCommand.Parameters.Add(new SqlParameter("@State", SqlDbType.NChar, 2));
myCommand.Parameters.Add(new SqlParameter("@Zip", SqlDbType.NChar, 5));
myCommand.Parameters.Add(new SqlParameter("@Contract", SqlDbType.NVarChar,1));
myCommand.Parameters["@Id"].Value = DataGrid1.DataKeys[(int)E.Item.ItemIndex];
String[] cols = {"@Id","@LName","@FName","@Phone","@Address","@City","@State","@Zip","@Contract"};
int numCols = E.Item.Cells.Count;
for (int i=2; i<numCols-1; i++) //跳過第一、第二和最后一列
{
String colvalue =((TextBox)E.Item.Cells[i].Controls[0]).Text;
// 檢查在所需字段中是否有空值
if (i<6 && colvalue == "")
{
Message.Text = "錯誤：“作者 ID”、“姓名”或“電話”不允許使用空值";
return;
}
myCommand.Parameters[cols[i-1]].Value = colvalue;
}
//追加最后一行，將 true/false 值轉(zhuǎn)換為 0/1
if (String.Compare(((TextBox)E.Item.Cells[numCols-1].Controls[0]).Text, "True", true)==0)
myCommand.Parameters["@Contract"].Value = "1";
else
myCommand.Parameters["@Contract"].Value = "0";
myCommand.Connection.Open();
try
{
myCommand.ExecuteNonQuery();
Message.Text = "<b>已更新記錄</b><br>" + updateCmd;
DataGrid1.EditItemIndex = -1;
}
catch (SqlException e)
{
if (e.Number == 2627)
Message.Text = "錯誤：已存在具有相同主鍵的記錄";
else
Message.Text = "錯誤：未能更新記錄，請確保正確填寫了字段";
}
myCommand.Connection.Close();
BindGrid();
}
public void BindGrid()
{
SqlDataAdapter myCommand = new SqlDataAdapter("select * from Authors", myConnection);
DataSet ds = new DataSet();
myCommand.Fill(ds, "Authors");
DataGrid1.DataSource=ds.Tables["Authors"].DefaultView;
DataGrid1.DataBind();
}
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