ASP.NET中使用数据处理插入数据注意的问题

很多时候，我们都会习惯将数据库连接的初始化过程交给Page_Load去做，其实这样子有好处也有坏处，好处是单边问题的时候，这种方法很实用，坏处就是遇到多边的问题时，就种情况这不太好用了！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"); //初始化过程
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); //初始化命令调用
//实现配套
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;
//打开DB
mySqlCom.Connection.Open();
mySqlCom.ExecuteNonQuery();
Message.InnerHtml = "<b>已添加记录</b><br/>";
mySqlCom.Connection.Close();
Pub_Id.Text = "";
Pub_Name.Text = "";
City.Text= "";
State.Text = "";
Country.Text = "";
BindGrid();
}
//子函数调用
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>添加一个新的发行者：</h2>
<br/>
发行者 ID 应以 99 打头，并包含 4 位数字<br/>
发行者 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/>
省：&nbsp;
<asp:textbox id="State" runat="server" />
国家：&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" />

这样的例子初初看起来没有问题，调试也没报错，但在生成的页面添加数据后提交时就会报错，说什么属性不配套之类的话。是什么原因造成的呢！其实，这就是初始化过程在页面装载时造成的，但这里有个问题我始终没能搞清楚，就是既然是在页面初始化过程已经初始化过DB实例了，按道理来讲应该可以直接生成套用的啊，但好像没有！还是要把初始化过程放到具体的函数里面才能实现！看下面:
<<script language="C#" runat="server">

protected void Page_Load(Object Src,EventArgs E)
{
//页面装载过程中直接使用IF语句，其实什么也不加！
if (!IsPostBack)
BindGrid();
}
public void AddPublisher(Object sender, EventArgs E)
{
string strprovider="server=localhost;uid=sa;pwd=sa;database=pubs"; //构造初始化过程
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); //初始化过程实现
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>已添加记录</b><br>";
mySqlCom.Connection.Close();
Pub_Id.Text = "";
Pub_Name.Text = "";
City.Text= "";
State.Text = "";
Country.Text = "";
BindGrid();
}
public void BindGrid() 子函数调用时同样也要初始化DB连接

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