如何在使用ASP.NET的插入代碼中處理異常？

Question

我在SQL Server Management Express中有一個名爲「Table_1」的表。我已經成功地將我的ASP程序連接到數據庫。我已經編碼了以下編碼以便在數據庫中插入數據。

ExecuteNonQuery: Connection property has not been initialized. 
    Description: An unhandled exception occurred during the execution of the current web  request. Please review the stack trace for more information about the error and where it originated in the code. 
    Exception Details: System.InvalidOperationException: ExecuteNonQuery: Connection property has not been initialized. 
    Source Error: 
    Line 34:    { 
    Line 35:     SqlCommand hi = new SqlCommand("insert into Table_1 values('" + TextBox1.Text + "','" + TextBox2.Text + "','" + TextBox3.Text + "','" + TextBox4.Text + "','" + TextBox5.Text + "','" + TextBox6.Text + "'),conn"); 
    Line 36:     hi.ExecuteNonQuery(); 
    Line 37:     conn.Close(); 
    Line 38:    } 

請幫我一個想法，以清除異常：

using System; 
    using System.Collections; 
    using System.Configuration; 
    using System.Data; 
    using System.Linq; 
    using System.Web; 
    using System.Web.Security; 
    using System.Web.UI; 
    using System.Web.UI.HtmlControls; 
    using System.Web.UI.WebControls; 
    using System.Web.UI.WebControls.WebParts; 
    using System.Xml.Linq; 
    using System.Data.SqlClient; 
    namespace k2 
    { 
    public partial class _Default : System.Web.UI.Page 
    { 
    SqlConnection conn = new SqlConnection("Data Source=ARTHY/SQLEXPRESS;Initial     Catalog=k2;Integrated Security=True"); 
    protected void Page_Load(object sender, EventArgs e) 
    {   
    } 
    protected void Button1_Click(object sender, EventArgs e) 
    { 
    try 
    { 
    conn.Open();   
    } 
    catch 
    { 
    SqlCommand hi = new SqlCommand("insert into Table_1 values('" + TextBox1.Text + "','" + TextBox2.Text + "','" + TextBox3.Text + "','" + TextBox4.Text + "','" + TextBox5.Text + "','" + TextBox6.Text + "'),conn"); 
    hi.ExecuteNonQuery(); 
    conn.Close(); 
    }  
    } 
    } 
    } 

當我試圖插入任何數據，我如下得到一個例外。

Answer 1

您的conn.Open()行位於try{}塊中，而其餘代碼位於catch{}塊中。所以，conn.Open()行會拋出異常，觸發catch{}，現在沒有conn引用。四處移動你的代碼：

try 
{ 
    conn.Open();   
    SqlCommand hi = new SqlCommand("insert into Table_1 values('" + TextBox1.Text + "','" + TextBox2.Text + "','" + TextBox3.Text + "','" + TextBox4.Text + "','" + TextBox5.Text + "','" + TextBox6.Text + "')", conn); 
    hi.ExecuteNonQuery(); 
    conn.Close(); 
} 
catch 
{ 
    //do something else if there is an exception 
} 

Answer 2

除了馬特的答案，我會建議包裝連接到using語句，以確保連接總是正確關閉。這裏是我的實現（重構一點點）

try 
{ 
    using (var connection = new SqlConnection("Data Source=ARTHY/SQLEXPRESS;Initial Catalog=k2;Integrated Security=True")) 
    { 
     connection.Open(); 
     var commandText = string.Format("insert into Table_1 values('{0}','{1}','{2}','{3}','{4}','{5}')", 
             TextBox1.Text, 
             TextBox2.Text, 
             TextBox3.Text, 
             TextBox4.Text, 
             TextBox5.Text, 
             TextBox6.Text); 

     var command = new SqlCommand(commandText, connection); 
     command.ExecuteNonQuery(); 
    } 
} 
catch (Exception exception) 
{ 
    // do something with exception 
}