Question

我将分享我的帮助班。当我使用SQLiteAddcustomer函数时，我得到了数据库锁定错误。我找到了一些解决方案＆＃34;使用＆＃34;声明，但问题仍在继续。我怎么解决这个问题？

public class SQLiteHelper
{
    String gDatabaseName = @"Data Source=RTM_Spark.sqlite;Version=3;";
    SQLiteConnection gConnection;
    SQLiteCommand gCommand;
    SQLiteDataReader gDataReader;
    SQLiteDataReader gDataReaderRoot;
    SQLiteDataReader gDataReaderDirectory;
    SQLiteDataReader gDataReaderCustomer;
    SQLiteDataReader gDataReaderDevice;

    public SQLiteHelper()
    {
        gDatabaseName = @"Data Source=RTM_Spark.sqlite;Version=3;";
    }

    public SQLiteHelper(String pDatabaseName)
    {
        gDatabaseName = String.Format("Data Source={0}", pDatabaseName);
    }

    public void SQLiteExecuteQuery(String pSQLCommand)
    {
        gCommand = new SQLiteCommand(gConnection);
        gCommand.CommandText = pSQLCommand;
        gCommand.ExecuteNonQuery();
    }

    public int SQLiteGetNodeID(String pSelectedNode)
    {
        int tSubID = 0;
        if (gConnection.State.ToString() == "Open")
        {
            gCommand = gConnection.CreateCommand();
            this.ExecuteNonQuery(String.Format("SELECT ID FROM tblNodes where isVisible=1 AND nodeName='{0}'", pSelectedNode));
            gDataReader = gCommand.ExecuteReader();
            while (gDataReader.Read())
            {
                tSubID = Convert.ToInt32(gDataReader["ID"]);
            }
        }
        return tSubID;
    }

    public int SQLiteGetNodeType(String pSelectedNode)
    {
        int tNodeType = 0;
        if (gConnection.State.ToString() == "Open")
        {
            gCommand = gConnection.CreateCommand();
            this.ExecuteNonQuery(String.Format("SELECT nodeType FROM tblNodes where isVisible=1 AND nodeName='{0}'", pSelectedNode));
            gDataReader = gCommand.ExecuteReader();
            while (gDataReader.Read())
            {
                tNodeType = Convert.ToInt32(gDataReader["nodeType"]);

            }
        }
        return tNodeType;
    }

    public void SQLiteAddCustomer(TreeNode pSelectedNode, String pCustomerName)
    {
        int tNodeType = 99;
        if (gConnection.State.ToString() == "Open")
        {
            gCommand = gConnection.CreateCommand();
            this.ExecuteNonQuery(String.Format("SELECT nodeType FROM tblNodes where isVisible=1 AND nodeName='{0}'", pCustomerName));
            SQLiteDataReader tDataReader = gCommand.ExecuteReader();
            while (tDataReader.Read())
            {
                tNodeType = Convert.ToInt32(gDataReader["nodeType"]);
            }
            if (tNodeType == 0 || tNodeType == 1 || tNodeType == 2)
            {
                MessageBox.Show(pCustomerName + " already saved on your list.");
            }
            else
            {
                int tSelectedID = SQLiteGetNodeID(pSelectedNode.Text);
                int tSelectedNodeType = SQLiteGetNodeType(pSelectedNode.Text);
                if (tSelectedNodeType == 0)
                {
                    gCommand = gConnection.CreateCommand();
                    this.ExecuteNonQuery(String.Format("INSERT INTO tblNodes (nodeName,nodeType,nodeSubID,isVisible) VALUES ('{0}',1,'{1}',1)", pCustomerName, tSelectedID));
                }
                else
                    MessageBox.Show("You can add Customer under directory");
            }
        }

    }

    public int ExecuteNonQuery(String pSQLCommand)
    {
        gConnection = new SQLiteConnection(gDatabaseName);
        gConnection.Open();
        gCommand = new SQLiteCommand(gConnection);
        gCommand.CommandText = pSQLCommand;
        int rowsUpdated = gCommand.ExecuteNonQuery();
        return rowsUpdated;

    }

    public void SQLiteOpenConnection()
    {
        gConnection = new SQLiteConnection(gDatabaseName);
        gConnection.Open();
    }

    public void SQLiteCloseConnection()
    {
        gConnection.Close();
    }

    public int SQLiteGetRootID()
    {
        int tRootID = 0;
        if (gConnection.State.ToString() == "Open")
        {
            gCommand = gConnection.CreateCommand();
            this.ExecuteNonQuery(String.Format("SELECT ID FROM tblNodes where nodeName='{0}'", "RTM Spark"));
            gDataReader = gCommand.ExecuteReader();
            while (gDataReader.Read())
            {
                tRootID = Convert.ToInt32(gDataReader["ID"]);
            }
        }
        gConnection.Close();
        return tRootID;
    }

    public void UpdateTreeView(TreeView pTreeView) 
    {
        refreshDatabaseConnection();
        pTreeView.Nodes.Clear();
        TreeNode rootNode = pTreeView.Nodes.Add("RTM Spark");
        getDirectoryNameQuery();
        while (gDataReaderRoot.Read())
        {
            String tDirectoryName = gDataReaderRoot["nodeName"].ToString();
            TreeNode directoryNode = rootNode.Nodes.Add(tDirectoryName);
            rootNode.ExpandAll();
            getDirectoryIDQuery(tDirectoryName);
            while (gDataReaderDirectory.Read())
            {
                int tDirectoryID = Convert.ToInt32(gDataReaderDirectory["ID"]);
                getCustomerNameQuery(tDirectoryID);
                while (gDataReaderDirectory.Read())
                {
                    String tCustomerName = gDataReaderDirectory["nodeName"].ToString();
                    TreeNode tCustomerNode = directoryNode.Nodes.Add(tCustomerName);
                    tCustomerNode.ExpandAll();
                    directoryNode.ExpandAll();
                    getCustomerIDQuery(tCustomerName);
                    while (gDataReaderCustomer.Read())
                    {
                        int tCustomerID = Convert.ToInt32(gDataReaderCustomer["ID"]);
                        getDeviceNameQuery(tCustomerID);
                        while (gDataReaderDevice.Read())
                        {
                            String tDeviceName = gDataReaderDevice["nodeName"].ToString();
                            TreeNode tDeviceNode = tCustomerNode.Nodes.Add(tDeviceName);
                            tDeviceNode.ExpandAll();
                            tCustomerNode.ExpandAll();
                            directoryNode.ExpandAll();
                        }
                    }
                }
            }
        }
    gConnection.Close();
    }

    public void refreshDatabaseConnection()
    {
        gConnection.Dispose();
        gConnection.Close();
        gConnection = new SQLiteConnection(gDatabaseName);
        gConnection.Open();
    }

    public void getDirectoryNameQuery()
    {
        int tRootID = SQLiteGetRootID();
        gCommand = gConnection.CreateCommand();
        this.ExecuteNonQuery(String.Format("SELECT nodeName from tblNodes where isVisible=1 AND nodeSubID='{0}'", tRootID));
        gDataReaderRoot = gCommand.ExecuteReader();
    }

    public void getDirectoryIDQuery(String pDirectoryName)
    {
        this.ExecuteNonQuery(String.Format("SELECT ID from tblNodes where isVisible=1 AND nodeName='{0}'", pDirectoryName));
        gDataReaderDirectory = gCommand.ExecuteReader();
    }

    public void getCustomerNameQuery(int pDirectoryID)
    {
        this.ExecuteNonQuery(String.Format("SELECT nodeName from tblNodes where isVisible=1 AND nodeSubID='{0}'", pDirectoryID));
        gDataReaderDirectory = gCommand.ExecuteReader();
    }

    public void getCustomerIDQuery(String pCustomerName)
    {
        this.ExecuteNonQuery(String.Format("SELECT ID from tblNodes where isVisible=1 AND nodeName='{0}'", pCustomerName));
        gDataReaderCustomer = gCommand.ExecuteReader();
    }

    public void getDeviceNameQuery(int pCustomerID)
    {
        this.ExecuteNonQuery(String.Format("SELECT nodeName from tblNodes where isVisible=1 AND nodeSubID='{0}'", pCustomerID));
        gDataReaderDevice = gCommand.ExecuteReader();
    }
}

}

Answer 1

您可以在助手类中使用锁定机制，在执行命令之前，您可以锁定并插入或更新。此锁定不允许其他线程进入此步骤以进行插入或删除。在你的帮助器中声明锁定对象

public static object LockObject = new object();

插入/更新前锁定

if (tSelectedNodeType == 0)
  {
          gCommand = gConnection.CreateCommand();
          lock(LockObject)
          {
              this.ExecuteNonQuery(String.Format("INSERT INTO tblNodes    (nodeName,nodeType,nodeSubID,isVisible) VALUES ('{0}',1,'{1}',1)", pCustomerName, tSelectedID));
        }
  }

插入查询时，SQLite数据库被锁定

1 个答案: