Datei bereits in Verwendung Ausnahme nach der Verwendung von dispose und SuppressFinalize auf MS-Zugriff Datei

Question

Ich arbeite an Software, die Änderungen in der Datenbank über die GUI vornehmen. Ich möchte die Datenbank komprimieren, nachdem der Benutzer auf Speichern geklickt hat. Nach dem Speichern kann der Benutzer die Software weiter benutzen oder schließen, also benutze ich nicht "using". Ich habe databaseAccess-Objekt erstellt, das OleDbConnection-Verbindungsobjekt mit wenigen anderen enthält. Dies ist meine Datenbankzugriffsklasse.

using System; 
using System.Collections.Generic; 
using System.Data.OleDb; 
using System.Data; 
using System.Diagnostics; 
using System.Windows.Forms; 

namespace TreeTool 
{ 
    public class DataBaseAccess 
    { 
     #region Properties 
     private string m_directory; 
     public List<string> selectedTableNames; 
     private Dictionary<String, DataTable> selectedTables; 
     private OleDbConnection mdbConnection; 
     DataTable dataTable; 

     //Constructor 
     public DataBaseAccess() 
     { 
      selectedTableNames = new List<string>(); 
      selectedTables = new Dictionary<string, DataTable>(); 
     } 

     public string directory 
     { 
      get 
      { 
       return m_directory; 
      } 
      set 
      { 
       m_directory = value; 
      } 
     } 
     #endregion 
     public List<string> GetAllTableNames() 
     { 
      if (dataTable != null) 
      { 
       List<string> tableList = new List<string>(); 
       for (int i = 0; i < dataTable.Rows.Count; i++) 
       { 
        string TableName = dataTable.Rows[i][2].ToString(); 
        tableList.Add(TableName); 
       } 
       return tableList; 
      } 
      return null; 
     } 

     /// <summary> 
     /// Returns Table Columns 
     /// </summary> 
     /// <returns></returns> 
     public DataTable GetTable(string TableName) 
     { 
      DataTable mdbTable; 
      if (selectedTables.TryGetValue(TableName, out mdbTable)) 
      { 
       return mdbTable; 
      } 
      else 
      { 
       mdbTable = new DataTable(); 
       //mdbConnection.Open(); 
       string mdbCommandString = "SELECT * FROM [" + TableName + "]"; 
       OleDbDataAdapter QueryCommand = new OleDbDataAdapter(mdbCommandString, mdbConnection); 
       QueryCommand.Fill(mdbTable); 
       //mdbConnection.Close(); 

       selectedTables.Add(TableName, mdbTable); 

       return mdbTable; 
      } 
     } 

     public void SetTable(String TableName, DataTable dataTable) 
     { 
      //mdbConnection.Open(); 

      OleDbCommand ac = new OleDbCommand("delete from [" + TableName + "]", mdbConnection); 
      ac.ExecuteNonQuery(); 

      foreach (DataRow row in dataTable.Rows) 
      { 
       String query = "INSERT INTO [" + TableName + "] (TaskID, HTMLTopic, nRelative, [Group], nKey," 
        + " [nText], nImage, nSelImage, nFontName, nFontInfo, Keywords) VALUES (@TaskID," 
        + " @HTMLTopic, @nRelative, @Group, @nKey, @nText, @nImage, @nSelImage, @nFontName, " 
        + " @nFontInfo, @Keywords)"; 
       OleDbCommand command = new OleDbCommand(query, mdbConnection); 
       command.Parameters.AddWithValue("@TaskID", row["TaskID"]); 
       command.Parameters.AddWithValue("@HTMLTopic", row["HTMLTopic"]); 
       command.Parameters.AddWithValue("@nRelative", row["nRelative"]); 
       command.Parameters.AddWithValue("@Group", row["Group"]); 
       command.Parameters.AddWithValue("@nKey", row["nKey"]); 
       command.Parameters.AddWithValue("@nText", row["nText"]); 
       command.Parameters.AddWithValue("@nImage", row["nImage"]); 
       command.Parameters.AddWithValue("@nSelImage", row["nSelImage"]); 
       command.Parameters.AddWithValue("@nFontName", row["nFontName"]); 
       command.Parameters.AddWithValue("@nFontInfo", row["nFontInfo"]); 
       command.Parameters.AddWithValue("@Keywords", row["Keywords"]); 
       command.ExecuteNonQuery(); 
      } 

      //mdbConnection.Close(); 
     } 

     internal bool validTable(string TableName) 
     { 
      DataTable mdbTable = new DataTable(); 

      //mdbConnection.Open(); 

      string mdbCommandString = "SELECT * FROM [" + TableName + "]"; 
      OleDbDataAdapter QueryCommand = new OleDbDataAdapter(mdbCommandString, mdbConnection); 
      QueryCommand.Fill(mdbTable); 
      //mdbConnection.Close(); 

      // check if table contains all columns necessary 
      String[] columnNames = new string[] { "TaskID" , "HTMLTopic", "nRelative", "Group", "nKey", 
       "nText", "nImage", "nSelImage", "nFontName", "nFontInfo", "Keywords"}; 

      Boolean missingColumn = false; 

      DataColumnCollection columns = mdbTable.Columns; 
      foreach (String columnName in columnNames) 
      { 
       if (columns.Contains(columnName) == false) 
       { 
        // print the message 
        MessageBox.Show("Database: " + directory + " Table: " + TableName + " is missing column \"" + columnName 
         + "\". Add it to make changes.", 
         "Missing column", 
         MessageBoxButtons.OK, 
         MessageBoxIcon.Exclamation, 
         MessageBoxDefaultButton.Button1); 
        missingColumn = true; 
       } 
      } 

      if (missingColumn == true) 
      { 
       return false; 
      } 
      return true; 
     } 

     public void insertTable(String tableName) 
     { 
      selectedTableNames.Add(tableName); 
     } 

     public List<String> getSelectedTables() 
     { 
      return selectedTableNames; 
     } 

     public Boolean isConnected() 
     { 
      if (mdbConnection == null) 
      { 
       return false; 
      } 
      return true; 
     } 

     public void connect() 
     { 
      if (mdbConnection == null) 
      { 
       String m_mdbDirectory = @"Provider=Microsoft.JET.OLEDB.4.0;Data Source=" + m_directory; 
       mdbConnection = new OleDbConnection(m_mdbDirectory); 
       mdbConnection.Open(); 
       string[] restrictions = new string[4]; 
       restrictions[3] = "Table"; 
       dataTable = mdbConnection.GetSchema("TABLES", restrictions); 
       //mdbConnection.Close(); 
      } 
     } 

     public void disconnect() 
     { 
      mdbConnection.Close(); 
      mdbConnection.Dispose(); 
      GC.SuppressFinalize(mdbConnection); 
      mdbConnection = null; 
     } 

     public void clearSelectedTables() 
     { 
      selectedTableNames.Clear(); 
     } 
    } 
} 

speichern und kompakte Funktionen sind wie diese

private void save() 
    { 
     foreach(DataBaseAccess database in databases) 
     { 
      // save changes code 
      database.disconnect(); 
      CompactAndRepairAccessDB(database.directory); 
      database.connect(); 
     } 
    } 

    private void CompactAndRepairAccessDB(string accessFile) 
    { 
     string tempFile = @"temp.mdb"; 
     FileInfo temp = new FileInfo(tempFile); 

     // Required COM reference for project: 
     // Microsoft Office 14.0 Access Database Engine Object Library 
     var dbe = new Microsoft.Office.Interop.Access.Dao.DBEngine(); 
     try 
     { 
      dbe.CompactDatabase(accessFile, tempFile); 
      temp.CopyTo(accessFile, true); 
      temp.Delete(); 
     } 
     catch (Exception e) 
     { 
      Console.WriteLine("Error: " + e.Message); 
     } 
    } 

Die Ausnahme auf Linie geschieht "dbe.CompactDatabase (Access, tempFile);".

Answer 1

In dem Code in allen Methoden, in denen Sie OleDbDataAdapter und OleDbCommand verwenden, stellen Sie sicher, das using-Muster für diese Objekte zu verwenden. Sie können die MDB-Datei geöffnet lassen, obwohl die Verbindung bereits besteht.

Methoden, die geändert werden müssen, scheinen GetTable, SetTable und ValidTable zu sein.