asp.net+Sqlite 时不时出现Unable to open the database file

[Netcean]

网站是能运行的起来，只不过时不时的会出现下面这个错误，没有规律的。app_data已经加了everyone写入权限了。
=================
Unable to open the database file
说明: 执行当前 Web 请求期间，出现未处理的异常。请检查堆栈跟踪信息，以了解有关该错误以及代码中导致错误的出处的详细信息。

异常详细信息: System.Data.SQLite.SQLiteException: Unable to open the database file

源错误:


行 162: {
行 163: if (connection.State != ConnectionState.Open)
行 164: connection.Open();
行 165: }
行 166:

===============================
下面是我的类部份方法，也以及及时的关闭了数据库连接。大家帮忙看看哪里还需要改进的。谢谢
[code=C#]
public class SQLiteHelper
{
public SQLiteHelper()
{

}
//数据库连接字符串(web.config来配置)，可以动态更改SQLString支持多数据库.
public static string connectionString = "Data Source=" + System.Web.HttpContext.Current.Server.MapPath(ConfigurationManager.AppSettings["ConnectionSQLite"]) + ";Version=3;";

public static SQLiteParameter GetOleDbParameter(string paraName, DbType type, int paraSize, Object value)
{
SQLiteParameter para = new SQLiteParameter(paraName, type, paraSize);
para.Value = value;
return para;
}
public static string GetTableData(string Fields, string ID)
{
string Sql = "select " + Fields + " From [table] where id='" + ID + "'";
return GetData(Sql);
}

public static string GetData(string Sql)
{
object obj = GetSingle(Sql);
if (obj == null)
{
return "";
}
return obj.ToString();
}

public static int GetMaxID(string FieldName, string TableName)
{
string strsql = "select max(" + FieldName + ")+1 from " + TableName;
object obj = GetSingle(strsql);
if (obj == null)
{
return 1;
}
else
{
return int.Parse(obj.ToString());
}
}

public static bool Exists(string strSql)
{
object obj = GetSingle(strSql);
int cmdresult;
if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
{
cmdresult = 0;
}
else
{
cmdresult = int.Parse(obj.ToString());
}
if (cmdresult == 0)
{
return false;
}
else
{
return true;
}
}

public static bool Exists(string strSql, params SQLiteParameter[] cmdParms)
{
object obj = GetSingle(strSql, cmdParms);
int cmdresult;
if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
{
cmdresult = 0;
}
else
{
cmdresult = int.Parse(obj.ToString());
}
if (cmdresult == 0)
{
return false;
}
else
{
return true;
}
}

#endregion

/// <summary>
/// 保证数据库连接处于打开状态
/// </summary>
/// <param name="connection"></param>
public static void OpenDb(SQLiteConnection connection)
{
if (connection.State != ConnectionState.Open)
connection.Open();
}

public static int ExecuteSql(string SQLString)
{
using (SQLiteConnection connection = new SQLiteConnection(connectionString))
{
using (SQLiteCommand cmd = new SQLiteCommand(SQLString, connection))
{
OpenDb(connection);
try
{
int rows = cmd.ExecuteNonQuery();
return rows;
}
catch (System.Data.SQLite.SQLiteException E)
{
throw new Exception(E.Message);
}
}
}
}

public static int ExecuteSql(string SQLString, string content)
{
using (SQLiteConnection connection = new SQLiteConnection(connectionString))
{
OpenDb(connection);
SQLiteCommand cmd = new SQLiteCommand(SQLString, connection);
using (cmd)
{
SQLiteParameter myParameter = new SQLiteParameter("@content", DbType.String);
myParameter.Value = content;
cmd.Parameters.Add(myParameter);
try
{
if (connection.State != ConnectionState.Open)
connection.Open();
int rows = cmd.ExecuteNonQuery();
return rows;
}
catch (System.Data.SQLite.SQLiteException E)
{
throw new Exception(E.Message);
}
finally
{
cmd.Dispose();
connection.Close();
}
}
}
}

[Netcean]

接着楼上的：

 public static object ExecuteSqlGet(string SQLString, string content)
    {
        using (SQLiteConnection connection = new SQLiteConnection(connectionString))
        {
            OpenDb(connection);
            using (SQLiteCommand cmd = new SQLiteCommand(SQLString, connection))
            {
                SQLiteParameter myParameter = new SQLiteParameter("@content", DbType.String);
                myParameter.Value = content;
                cmd.Parameters.Add(myParameter);
                try
                {
                    if (connection.State != ConnectionState.Open)
                        connection.Open();
                    object obj = cmd.ExecuteScalar();
                    if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
                    {
                        return null;
                    }
                    else
                    {
                        return obj;
                    }
                }
                catch (System.Data.SQLite.SQLiteException E)
                {
                    throw new Exception(E.Message);
                }
                finally
                {
                    cmd.Dispose();
                    connection.Close();
                }
            }
        }
    }

    public static int ExecuteSqlInsertImg(string strSQL, byte[] fs)
    {
        using (SQLiteConnection connection = new SQLiteConnection(connectionString))
        {
            OpenDb(connection);
            using (SQLiteCommand cmd = new SQLiteCommand(strSQL, connection))
            {
                SQLiteParameter myParameter = new SQLiteParameter("@fs", DbType.Binary);
                myParameter.Value = fs;
                cmd.Parameters.Add(myParameter);
                try
                {
                    if (connection.State != ConnectionState.Open)
                        connection.Open();
                    int rows = cmd.ExecuteNonQuery();
                    return rows;
                }
                catch (System.Data.SQLite.SQLiteException E)
                {
                    throw new Exception(E.Message);
                }
                finally
                {
                    cmd.Dispose();
                    connection.Close();
                }
            }
        }
    }

    public static object GetSingle(string SQLString)
    {
        using (SQLiteConnection connection = new SQLiteConnection(connectionString))
        {
            OpenDb(connection);
            using (SQLiteCommand cmd = new SQLiteCommand(SQLString, connection))
            {
                try
                {
                    object obj = cmd.ExecuteScalar();
                    if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
                    {
                        return null;
                    }
                    else
                    {
                        return obj;
                    }
                }
                catch (System.Data.SQLite.SQLiteException e)
                {
                    //connection.Close();
                    throw new Exception(e.Message);
                }
                finally
                {
                    connection.Close();
                    cmd.Dispose();
                }
            }
        }
    }

    public static DataSet Query(string SQLString)
    {

        using (SQLiteConnection connection = new SQLiteConnection(connectionString))
        {
            OpenDb(connection);
            try
            {
                DataSet ds = new DataSet();
                using (SQLiteDataAdapter command = new SQLiteDataAdapter(SQLString, connection))
                {
                    command.Fill(ds, "ds");
                }
                return ds;
            }
            catch (System.Data.SQLite.SQLiteException ex)
            {
                throw new Exception(ex.Message);
            }
        }

    }

    public static DataSet Query(string SQLString, string TableName)
    {
        using (SQLiteConnection connection = new SQLiteConnection(connectionString))
        {
            OpenDb(connection);
            DataSet ds = new DataSet();
            try
            {
                SQLiteDataAdapter command = new SQLiteDataAdapter(SQLString, connection);
                using (command)
                {
                    command.Fill(ds, TableName);
                }
            }
            catch (System.Data.SQLite.SQLiteException ex)
            {
                throw new Exception(ex.Message);
            }
            return ds;


        }
    }
    public static DataSet Query(string SQLString, int Times)
    {
        using (SQLiteConnection connection = new SQLiteConnection(connectionString))
        {
            OpenDb(connection);
            DataSet ds = new DataSet();
            try
            {
                SQLiteDataAdapter command = new SQLiteDataAdapter(SQLString, connection);
                using (command)
                {
                    command.SelectCommand.CommandTimeout = Times;
                    command.Fill(ds, "ds");
                }
                return ds;
            }
            catch (System.Data.SQLite.SQLiteException ex)
            {
                throw new Exception(ex.Message);
            }


        }
    }

    public static int ExecuteSql(string SQLString, params SQLiteParameter[] cmdParms)
    {
        using (SQLiteConnection connection = new SQLiteConnection(connectionString))
        {
            OpenDb(connection);
            using (SQLiteCommand cmd = new SQLiteCommand())
            {
                try
                {
                    PrepareCommand(cmd, connection, null, SQLString, cmdParms);
                    int rows = cmd.ExecuteNonQuery();
                    cmd.Parameters.Clear();
                    return rows;
                }
                catch (System.Data.SQLite.SQLiteException E)
                {
                    throw new Exception(E.Message);
                }
            }
        }
    }

[xuan.ye]

sqllite 不支持多个线程同时写入，对于b/s，不应该使用

[Netcean]

多人同时向sqlite插入数据的话，容易出错？

[Netcean]

刚找到一篇文章：
SQLite省略了一些人们认为比较有用的特性, 例如高并发性、 严格的存取控制、 丰富的内置功能、 存储过程、复杂的SQL语言特性、
SQLite最佳试用场合

网站
嵌入式设备和应用软件
应用程序文件格式
。。。。。


估计是我上面的操作类写的不够严谨。

[Netcean]

大家帮忙想想会是哪里出了问题。谢谢

[bakdfkuk]

[Quote=引用 2 楼 yeness 的回复:]

sqllite 不支持多个线程同时写入，对于b/s，不应该使用
[/Quote]
以前我好像用过多线程的。。。。。。。。
楼主这个问题还是等高手来吧，我是看到这么多代码就退下来了

[Netcean]

那些代码都是操作数据库的。就是普通的读取到DataSet,DataTable 执行SQL语句之类的

[sweatypalms]

我也遇到了同样的问题，终于解决了connectionstring里面要加上";Pooling=True",sqllite默认没有打开连接池。要指定。

[meic1985]

学习了

[Netcean]

谢谢sweatypalms，我的连接代码改成如下：
<add key="ConnectionSQLite" value="App_Data/test.db3"/>

Data Source=" + System.Web.HttpContext.Current.Server.MapPath(ConfigurationManager.AppSettings["ConnectionSQLite"]) + ";Version=3;Pooling=True;
===============
不知跟你的是否一样，能贴出你的代码吗？你现在还有出现这错误么？

[Netcean]

这个帖又要以无解收场么？

[xuan.ye]

[Quote=引用 11 楼 netcean 的回复:]

这个帖又要以无解收场么？
[/Quote]
只要换成mysql就可以解决了。

[Netcean]

现在数据库已经是采用Sqlite了，换mysql是不可能了。

[Wicho开源开发中]

没有可不可能，只是你想不想去做

[xuan.ye]

using (SQLiteConnection connection = new SQLiteConnection(connectionString))
{
OpenDb(connection);
SQLiteCommand cmd = new SQLiteCommand(SQLString, connection);
using (cmd)
{
SQLiteParameter myParameter = new SQLiteParameter("@content", DbType.String);
myParameter.Value = content;
cmd.Parameters.Add(myParameter);
try
{
if (connection.State != ConnectionState.Open)
connection.Open();
int rows = cmd.ExecuteNonQuery();
return rows;
}
catch (System.Data.SQLite.SQLiteException E)
{
throw new Exception(E.Message);
}
finally
{
cmd.Dispose();
connection.Close();
}
}
这样的代码有问题，using 相当于 try finally,这样的话finally里面很可能报异常，但应该不影响数据库

[袁圈er]

不允许多线程访问，2楼正解。我就是这样解决的：http://duan.es

[RLib]

引用 8 楼 sweatypalms 的回复:

我也遇到了同样的问题，终于解决了connectionstring里面要加上";Pooling=True",sqllite默认没有打开连接池。要指定。

效果如何