ASP.NET中使用數據處理插入數據注意的問題

    很多時候，我們都會習慣將數據庫連接的初始化過程交給Page_Load去做，其實這樣子有好處也有壞處，好處是單邊問題的時候，這種方法很實用，壞處就是遇到多邊的問題時，就種情況這不太好用了！例如下面的例子：

/// For Example:

<script language="C#" runat="server">
SqlConnection mySqlCon;
protected void Page_Load(Object Src,EventArgs E)
{
mySqlCon=new SqlConnection("server=localhost;uid=sa;pwd=sa;database=pubs"); //初始化過程
if (!IsPostBack)
BindGrid();
}
public void AddPublisher(Object sender, EventArgs E)
 {
String myinsertCmd = "insert into publishers ( pub_id, pub_name, city, state, country ) values (@pubid,@pubname,@city,@state,@country)";
SqlCommand mySqlCom = new SqlCommand(myinsertCmd, mySqlCon);  //初始化命令調用
//實現配套
mySqlCom.Parameters.Add(new SqlParameter("@pubid", SqlDbType.Char, 4));
mySqlCom.Parameters["@pubid"].Value = Pub_Id.Text;
mySqlCom.Parameters.Add(new SqlParameter("@pubname", SqlDbType.VarChar, 40));
mySqlCom.Parameters["@pubname"].Value = Pub_Name.Text;
mySqlCom.Parameters.Add(new SqlParameter("@city", SqlDbType.VarChar, 20));
mySqlCom.Parameters["@city"].Value = City.Text;
mySqlCom.Parameters.Add(new SqlParameter("@state", SqlDbType.Char, 2));
mySqlCom.Parameters["@state"].Value = State.Text;
mySqlCom.Parameters.Add(new SqlParameter("@country",SqlDbType.VarChar, 30));
mySqlCom.Parameters["@country"].Value = Country.Text;
//打開DB
mySqlCom.Connection.Open();
mySqlCom.ExecuteNonQuery();
Message.InnerHtml = "<b>已添加記錄</b><br/>";
mySqlCom.Connection.Close();
Pub_Id.Text = "";
Pub_Name.Text = "";
City.Text= "";
State.Text = "";
Country.Text = "";
BindGrid();
}
//子函數調用
public void BindGrid()
{
SqlDataAdapter mySqlCom = new SqlDataAdapter("select * from publishers where pub_id like '99%'", mySqlCon);
DataSet myds = new DataSet();
mySqlCom.Fill(myds, "publishers");
dgMyGrid.DataSource = myds.Tables["publishers"].DefaultView; dgMyGrid.DataBind();
}
</script>
<h2>添加一個新的發行者：</h2>
<br/>
發行者 ID 應以 99 打頭，并包含 4 位數字<br/>
發行者 ID：&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;
<asp:textbox id="Pub_Id" runat="server" />姓名：&nbsp;&nbsp;
<asp:textbox id="Pub_Name" runat="server" />
城市：&nbsp;
<asp:textbox id="City" runat="server" />
<br/>
�。�&nbsp;
<asp:textbox id="State" runat="server" />
國家：&nbsp;
<asp:textbox id="Country" runat="server" />
<br/>
<br/>
&nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
<asp:button Text="提交" OnClick="AddPublisher" runat="server" ID="Button1" /><br/>
<span id="Message" runat="server" />
<br/>
<asp:DataGrid id="dgMyGrid" runat="server" />

這樣的例子初初看起來沒有問題，調試也沒報錯，但在生成的頁面添加數據后提交時就會報錯，說什么屬性不配套之類的話。是什么原因造成的呢！其實，這就是初始化過程在頁面裝載時造成的，但這里有個問題我始終沒能搞清楚，就是既然是在頁面初始化過程已經初始化過DB實例了，按道理來講應該可以直接生成套用的啊，但好像沒有！還是要把初始化過程放到具體的函數里面才能實現！看下面:
<<script language="C#" runat="server">
  
   protected void Page_Load(Object Src,EventArgs E)
   {
   //頁面裝載過程中直接使用IF語句，其實什么也不加！
   if (!IsPostBack)
   BindGrid();
   }  
   public void AddPublisher(Object sender, EventArgs E)
    {
   string strprovider="server=localhost;uid=sa;pwd=sa;database=pubs"; //構造初始化過程
   SqlConnection mySqlCon=new SqlConnection(strprovider);
   string myinsertCmd ="insert into publishers ( pub_id, pub_name, city, state, country ) values (@pubid,@pubname,@city,@state,@country)";
   SqlCommand mySqlCom = new SqlCommand(myinsertCmd,mySqlCon);   //初始化過程實現
   mySqlCom.Parameters.Add(new SqlParameter("@pubid", SqlDbType.Char, 4));
   mySqlCom.Parameters["@pubid"].Value = Pub_Id.Text;
   mySqlCom.Parameters.Add(new SqlParameter("@pubname", SqlDbType.VarChar, 40));
   mySqlCom.Parameters["@pubname"].Value = Pub_Name.Text;
   mySqlCom.Parameters.Add(new SqlParameter("@city", SqlDbType.VarChar, 20));
   mySqlCom.Parameters["@city"].Value = City.Text;
   mySqlCom.Parameters.Add(new SqlParameter("@state", SqlDbType.Char, 2));
   mySqlCom.Parameters["@state"].Value = State.Text;
   mySqlCom.Parameters.Add(new SqlParameter("@country",SqlDbType.VarChar, 30));
   mySqlCom.Parameters["@country"].Value = Country.Text;
   mySqlCom.Connection.Open();
   mySqlCom.ExecuteNonQuery();
   Message.InnerHtml = "<b>已添加記錄</b><br>";
   mySqlCom.Connection.Close();
   Pub_Id.Text = "";
   Pub_Name.Text = "";
   City.Text= "";
   State.Text = "";
   Country.Text = "";
   BindGrid();
   }
    public void BindGrid()  子函數調用時同樣也要初始化DB連接
    {
    string strprovider="server=dev;uid=sa;pwd=pauperboyboy;database=pubs";
    SqlConnection mySqlCon=new SqlConnection(strprovider);
    SqlDataAdapter mySqlCom = new SqlDataAdapter("select * from publishers where pub_id like '99%'",mySqlCon);
    DataSet myds = new DataSet();
    mySqlCom.Fill(myds, "publishers");
    dgMyGrid.DataSource = myds.Tables["publishers"].DefaultView;
    dgMyGrid.DataBind();
    }
   </script>
   <h2>添加一個新的發行者：</h2>
   <br>
   發行者 ID 應以 99 打頭，并包含 4 位數字<br>
   發行者 ID：&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;
   <asp:textbox id="Pub_Id" runat="server" />姓名：&nbsp;&nbsp;
   <asp:textbox id="Pub_Name" runat="server" />
   城市：&nbsp;
   <asp:textbox id="City" runat="server" />
   <br>
   �。�&nbsp;
   <asp:textbox id="State" runat="server" />
   國家：&nbsp;
   <asp:textbox id="Country" runat="server" />
   <br>
   <br>
   &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
   <asp:button Text="提交" OnClick="AddPublisher" runat="server" ID="Button1" /><br>
   <span id="Message" runat="server" />
   <br>
   <asp:DataGrid id="dgMyGrid" runat="server" />
  </form>>

經過這樣修改后，我們才能在真正意義上實現數據的增加！但我也試了數據的刪除和更新，在頁面裝載時直接賦于其初始化DB屬性卻沒有問題，不知道是什么原因，知道的人給提個醒哦！謝謝 :)