無法從C＃.NET更新Access數據庫文件

Question

我嘗試使用Visual C＃學習一些編碼。我創建了一個用於添加和更新Access數據庫的表單。

我可以成功添加到Access文件，但我無法更新它們。

我寫的代碼在網上搜索一些下面相似，但我得到這個錯誤：

ExecuteNonQuery requires an open and available Connection. The connection's current state is closed.

我的代碼是：

public partial class form1 : Form 
{ 
    private OleDbConnection con; 

    private void btnUpDate_Click(object sender, EventArgs e) 
    { 
      string FirstName = txtFirstName.Text; 
      string Family = txtFamily.Text; 
      string City = txtCity.Text; 
      string approve = txtapprove.Text; 
      string OfficeNumber = txtOfficeNumber.Text; 
      string OfficialDossier = txtOfficialDossier.Text; 
      string Department = txtDepartment.Text; 
      string Organization = txtOrganization.Text; 

      OleDbConnection oleDBConn = new OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=Data Source=F:\\Database.accdb"); 
      string query = "UPDATE Sheet1 SET FirstName=@FirstName, Family=@Family, City=@City, approve=@approve, OfficeNumber=@OfficeNumber, OfficialDossier=@OfficialDossier, Department=@Department, Organization=@Organization WHERE OfficeNumber=@OfficeNumber"; 

      //string query = "UPDATE aspnet_Users SET FirstName=@FirstName, Family=@Family, City=@City, approve=@approve, OfficeNumber=@OfficeNumber, OfficialDossier=@OfficialDossier, Department=@Department WHERE OfficeNumber=@OfficeNumber"; 

      OleDbCommand cmd = new OleDbCommand(query, oleDBConn); 
      cmd.CommandType = CommandType.Text; 
      cmd.Parameters.AddWithValue("@OfficeNumber", OfficeNumber); 
      cmd.Parameters.AddWithValue("@OfficialDossier", OfficialDossier); 
      cmd.Parameters.AddWithValue("@FirstName", FirstName); 
      cmd.Parameters.AddWithValue("@Family", Family); 
      cmd.Parameters.AddWithValue("@City", City); 
      cmd.Parameters.AddWithValue("@approve", approve); 
      cmd.Parameters.AddWithValue("@Department", Department); 
      cmd.Parameters.AddWithValue("@Organization", Organization); 

      try 
      { 
       con.Open(); 

       int result = cmd.ExecuteNonQuery(); 

       if (result > 0) 
        MessageBox.Show("Success!"); 
       else 
        MessageBox.Show("Sorry!"); 
      } 
      catch (OleDbException) 
      { 
       MessageBox.Show("There is a problem!"); 
      } 
      finally 
      { 
       con.Close(); 
      } 
     } 
    } 

我哪裏有錯？我不使用DataSet和DataAdapter。那裏有問題嗎？

我使用VS 2010

Answer 1

問題1：你沒有打開，其被分配到OleDbCommand對象的Connection對象oleDBConn。

已分配oleDBConn給OleDbCommand對象如下：

OleDbCommand cmd = new OleDbCommand(query, oleDBConn);//here you have assigned oleDbConn 

，但你已經打開了如下不同ConnectionObject con：

con.Open(); 

解決方案1：

替換此：您應該始終打開OleDbConnection（oleDBConn）對象wh ich被分配給OleDbCOmmand對象。

con.Open(); 

這一點：

oleDBConn.Open(); 

問題2：您已經創建了一個額外的連接對象con（您btnUpDate_Click功能的頂部）和錯誤您正在使用相同的（開放工作。並關閉錯誤的連接對象而不是正確的連接對象）

解決方案2：刪除在上面創建的額外連接對象btnUpDate_Click功能並用oleDBConn替換所有con發生。

完整代碼：

try 
{ 
oleDBConn.Open(); 

int result = cmd.ExecuteNonQuery(); 

if (result > 0) 
MessageBox.Show("Success!"); 
else 
MessageBox.Show("Sorry!"); 
} 
catch (OleDbException ex) 
{ 
MessageBox.Show("There is a problem!"+ex.ToString()); 
} 
finally 
{ 
oleDBConn.Close(); 
}