错误告诉我我没有关闭连接，但是不是吗? [英] Error tells me I haven't close the connection, but haven't I?

问题描述

我一定在这里错过了一些东西.我正在尝试创建表，但收到一条错误消息，告诉我连接仍处于打开状态.但是哪里???我已经重新阅读了代码，但是找不到连接仍然打开的地方...

I must have missed something here. I am trying to create a table but I am getting an error telling me that connection is still open. But where??? I have re-read the code but I can't find where the connection is still open...

问题出现在这里:objOleDbConnection.Open()

错误提示:

You attempted to open a database that is already opened by user 'Admin' on machine 'machine'. Try again when the database is available.

private void sfdNewFile_FileOk(object sender, System.ComponentModel.CancelEventArgs e)
{
    // Creating a ADOX object needed to create
    // new MS Access file.
    ADOX.Catalog createMSFile = new ADOX.Catalog();
    // Creating an object for a table.
    Table nTable = new Table();

    // Creating an object allowing me connecting to the database.
    OleDbConnection objOleDbConnection = new OleDbConnection();
    objOleDbConnection.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;" +
            "Data Source=" + sfdNewFile.FileName + ";Persist Security Info=False;Mode=12";
    // Creating command object.
    OleDbCommand objOleDbCommand = new OleDbCommand();
    objOleDbCommand.Connection = objOleDbConnection;

    try
    {
        // Created a new MS Access 2007 file with specified path.
        createMSFile.Create("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" +
            sfdNewFile.FileName);

        objOleDbConnection.Open();
        objOleDbCommand.CommandText = "CREATE TABLE PersonalData (" +
            "[DataID] AUTOINCREMENT NOT NULL PRIMARY KEY ," +
            "[Type] VARCHAR(40) NOT NULL ," +
            "[URL] VARCHAR(40) NOT NULL ," +
            "[SoftwareName] VARCHAR(40) NOT NULL ," +
            "[SerialCode] VARCHAR(40) NOT NULL ," +
            "[UserName] VARCHAR(40) NOT NULL ," +
            "[Password] VARCHAR(40) NOT NULL";

        objOleDbCommand.ExecuteNonQuery();
    }
    catch (Exception ex)
    {
        // Displaying any errors that 
        // might have occured.
        MessageBox.Show("Error: " + ex.Message);
    }
    finally
    {
        // It is importnat to release COM object, in this very order
        // otherwise we eill end up with an error.
        System.Runtime.InteropServices.Marshal.FinalReleaseComObject(createMSFile);

        // Closing the connection to the database.
        objOleDbConnection.Close();
    }
}

推荐答案

似乎ADOX对象也应该关闭其连接. 查看来自Microsoft的以下示例: http://msdn.microsoft. com/en-us/library/windows/desktop/ms681562(v = vs.85).aspx

It seems that the ADOX object should close its connection as well. Look at the following sample from Microsoft: http://msdn.microsoft.com/en-us/library/windows/desktop/ms681562(v=vs.85).aspx

他们的ADOX对象被命名为cat. 它们具有以下内容:

Their ADOX object is named cat. They have the following:

cat.ActiveConnection = Nothing

这可能会翻译为:

createMSFile.ActiveConnection = null

在您的代码中(可能在第一个Final代码块中). 我认为是ADOX对象有所作为，在分配它之前，尝试将其ActiveConnection设置为null.

In your code (probably in the first Finally block). I think it's the ADOX object that makes the difference, before dispoing it, try to set it's ActiveConnection to null.

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