C# 无法连接本地数据库

Question

因此，我有以下代码用于连接数据库并将记录插入数据库：

string dbfile = "|DataDirectory|\\Databases\\Database.sdf";
            SqlConnection connection = new SqlConnection("Data Source=" + dbfile);
            SqlCommand query = new SqlCommand("insert into Leggers values('" + leggernummer + "','" + omschrijving + "')", connection);
            ** connection.Open(); **
            query.BeginExecuteNonQuery();

            connection.Close();

我的配置文件如下所示：

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <configSections>
    </configSections>
    <connectionStrings>
        <add name="connectionstring"
            connectionString="Data Source=|DataDirectory|\Databases\Database.sdf"
            providerName="Microsoft.SqlServerCe.Client.3.5" />
    </connectionStrings>
</configuration>

然后它在第一个代码块中 ** 和 ** 之间的部分给出错误

错误是：

System.Data.SqlClient.SqlException was unhandled
  Message=A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)
  Source=.Net SqlClient Data Provider
  ErrorCode=-2146232060
  Class=20
  LineNumber=0
  Number=-1
  Server=""
  State=0
  StackTrace:
       at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection)
       at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning()
       at System.Data.SqlClient.TdsParser.Connect(ServerInfo serverInfo, SqlInternalConnectionTds connHandler, Boolean ignoreSniOpenTimeout, Int64 timerExpire, Boolean encrypt, Boolean trustServerCert, Boolean integratedSecurity)
       at System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, Boolean ignoreSniOpenTimeout, TimeoutTimer timeout, SqlConnection owningObject)
       at System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(ServerInfo serverInfo, String newPassword, Boolean redirectedUserInstance, SqlConnection owningObject, SqlConnectionString connectionOptions, TimeoutTimer timeout)
       at System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(SqlConnection owningObject, TimeoutTimer timeout, SqlConnectionString connectionOptions, String newPassword, Boolean redirectedUserInstance)
       at System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, Object providerInfo, String newPassword, SqlConnection owningObject, Boolean redirectedUserInstance)
       at System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection)
       at System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnection owningConnection, DbConnectionPool pool, DbConnectionOptions options)
       at System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject)
       at System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject)
       at System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject)
       at System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection)
       at System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory)
       at System.Data.SqlClient.SqlConnection.Open()
       at Stockbeheer_Savenay.Forms.LeggerToevoegen.addItem(String leggernummer, String omschrijving) in C:\Users\Simon\Desktop\Stockbeheer Savenay\Stockbeheer Savenay\Forms\LeggerToevoegen.cs:line 59
       at Stockbeheer_Savenay.Forms.LeggerToevoegen.btnToevoegen_Click(Object sender, EventArgs e) in C:\Users\Simon\Desktop\Stockbeheer Savenay\Stockbeheer Savenay\Forms\LeggerToevoegen.cs:line 31
       at System.Windows.Forms.Control.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
       at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
       at System.Windows.Forms.Control.WndProc(Message& m)
       at System.Windows.Forms.ButtonBase.WndProc(Message& m)
       at System.Windows.Forms.Button.WndProc(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
       at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.Run(Form mainForm)
       at Stockbeheer_Savenay.Program.Main() in C:\Users\Simon\Desktop\Stockbeheer Savenay\Stockbeheer Savenay\Classes\Program.cs:line 18
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException: 

我是对 C# 中的数据库不熟悉，所以我不确定出了什么问题。尝试遵循教程，但它们都说不同的东西，所以很难弄清楚我到底应该做什么。

谢谢！

Answer 1

使用 .sdf 文件（SQL Server Compact Edition）时，需要使用 SqlCeConnection 而不 SqlConnection（适用于完整的 SQL Server）：

string dbfile = "|DataDirectory|\\Databases\\Database.sdf";

string insertStmt = "insert into Leggers values('" + leggernummer + "','" + omschrijving + "')";

using(SqlCeConnection connection = new SqlCeConnection("Data Source=" + dbfile))
using(SqlCeCommand query = new SqlCeCommand(insertStmt, connection))
{
    connection.Open();
    query.BeginExecuteNonQuery();
    connection.Close();
}

另外：您应该尝试使用参数化查询，而不仅仅是将 SQL 语句连接在一起......（研究“SQL 注入攻击” ....)