asp.net 2.0下用access開發的時候要注意的問題

很煩很煩,做的時候,煩到很難過很難受

1、數據庫要給訪問權限,在我的電腦裏,右擊access數據庫,點擊“屬性”菜單,選“安全”選項卡,選擇Users組,賦給完全控制的權限

  如果沒有安全選項卡,點擊菜單“工具”->“文件夾選項”,進入“查看”選項卡,把“使用簡單文件共享”前的勾去掉

2、連接數據庫的時候,如果想要做到可以隨時更改數據庫的名稱,也不用重新編譯網站,就把數據庫的路徑記錄在web.config文件裏:

    <connectionStrings>
      <add name="aceConnectionString" connectionString="目錄//數據庫名稱.mdb" providerName="System.Data.OleDb" />
    </connectionStrings>

  使用這兩個方法取值:

public static string connectString = "Provider=Microsoft.Jet.OleDb.4.0;Data Source=" + HttpContext.Current.Server.MapPath(ConfigurationManager.ConnectionStrings["aceConnectionString"].ConnectionString);

  public static string GetDB()
    {
        return HttpContext.Current.Server.MapPath(ConfigurationManager.ConnectionStrings["aceConnectionString"].ConnectionString);
    }

在每個頁面,如果用到AccessDataSource控件,這個控件是不會自己讀取這個值的,可以在Page_Load頁面裏,使用AdsAd.DataFile = NnllClass.GetDB();給他賦值

protected void Page_Load(object sender, EventArgs e)
    {
        AdsAd.DataFile = NnllClass.GetDB();
    }

3、如果使用AccessDataSource添加、刪除、修改記錄,要注意參數的問題,有一些網站,對一些參數報錯的信息,給出的答案說access數據庫應該使用拼接的sql語句,不可以使用參數,這種說法是不對的,access數據庫也可以使用參數傳遞的方式增刪改查數據庫的

就是,因爲vs.net 2005不可以像使用ms sql時一樣子,自動會檢索出參數,所以全部參數要自己手動添加,在添加參數的時候,要很小心,不要少了,也不要多了,也不要搞亂了順序

發現AccessDataSource控件,好像是根據綁定字段的順序來對應傳入的參數的,也就是說,如果你在FormView裏,是這樣子綁定的:

<asp:TextBox ID="myField1TextBox" runat="server" Text='<%# Bind("myField1") %>' MaxLength="20"></asp:TextBox>
<asp:TextBox ID="myField2TextBox" runat="server" Text='<%# Bind("myField2") %>' MaxLength="20"></asp:TextBox>

定義參數的時候,就應該這樣子定義:

 <InsertParameters>
            <asp:Parameter Name="myField1" Type="String" Size="20" ConvertEmptyStringToNull="False" />
            <asp:Parameter Name="myField2" Type="String" Size="20" ConvertEmptyStringToNull="False" />
        </InsertParameters>

次序不要搞亂了,搞亂了數據格式不同時,會報錯,具體的出錯信息我忘記了

定義參數的時候,還有一個要注意的問題就是,參數名不要寫錯,參數不要寫漏

使用sql數據庫時,參數名不對,或者參數個數不對,都會得到很明顯的出錯信息,就是,access數據庫,在這種時候,是不報錯的,如果參數名寫錯了,只會說有n個參數沒有值,如果是寫漏了參數,他有時候會直接替你更新數據庫,而更新的時候,是以綁定的順序來對應參數的值的,這時候,如果後面的參數值,大於前面的參數對應的字段大小,就會得到“字段太小”的出錯信息

 

<InsertParameters>
            <asp:Parameter Name="myField1" Type="String" Size="20" ConvertEmptyStringToNull="False" />
            <asp:Parameter Name="myField2" Type="String" Size="20" ConvertEmptyStringToNull="False" />
        </InsertParameters>

如果少了一個

            <asp:Parameter Name="myField3" Type="String" Size="200" ConvertEmptyStringToNull="False" />

在更新的時候,會把myField3的值,寫進myField2裏,如果myField3的值的長度大於20,就會報“字段太小”了

3、如果不習慣AccessDataSource控件,那就自己綁定數據吧,給出一些方法:

#region 返回數據庫地址
    public static string GetDB()
    {
        return HttpContext.Current.Server.MapPath(ConfigurationManager.ConnectionStrings["aceConnectionString"].ConnectionString);
    }
    #endregion

   

#region 打開數據庫:SqlConnection OpenConnect()
    public OleDbConnection OpenConnect(Page aPage,bool setMsg)
    {
        try
        {
            OleDbConnection dbConnect = new OleDbConnection(connectString);
            if (!dbConnect.State.Equals(ConnectionState.Open))
            {
                dbConnect.Open();
            }
            return dbConnect;
        }
        catch (OleDbException ex)
        {
            if (setMsg)
            {
                SetMsgJS(aPage.Master, "連接數據庫失敗:" + ex.Message.Replace("/n", "").Replace("/r", ""));
            }
            return null;
        }
    }
    #endregion

   

#region 關閉數據庫:void CloseConnect(SqlConnection dbConnect)
    public void CloseConnect(OleDbConnection dbConnect)
    {
        if (dbConnect.State.Equals(ConnectionState.Open))
        {
            dbConnect.Close();
        }
    }
    #endregion

   

#region 讀取數據,返回DataSet
    public DataSet GetDataSet(Page aPage, OleDbConnection dbConnection, CommandType commandType, string commandText, out string msg, bool setMsg)
    {
        msg = "";

        //創建並設置SqlCommand
        OleDbCommand dbCommand = new OleDbCommand();
        dbCommand.Connection = dbConnection;
        dbCommand.CommandType = commandType;
        dbCommand.CommandText = commandText;
        //創建SqlDataAdapter並獲取數據
        DataSet ds = new DataSet();
        try
        {
            OleDbDataAdapter dataAdapter = new OleDbDataAdapter(dbCommand);
            dataAdapter.Fill(ds);
        }
        catch (InvalidOperationException eo)
        {
            msg = "讀取數據失敗:" + eo.Message.Replace("/n", "").Replace("/r", "") + "//n";
            if (setMsg)
            {
                SetMsgJS(aPage.Master, msg);
            }
        }
        catch (OleDbException ex)
        {
            msg = "讀取數據失敗:" + ex.Message.Replace("/n", "").Replace("/r", "") + "//n";
            if (setMsg)
            {
                SetMsgJS(aPage.Master, msg);
            }
        }

        //返回數據
        return ds;
    }
    #endregion

   

#region 讀取數據,返回SqlDataReader
    public OleDbDataReader GetDataReader(Page aPage, OleDbConnection dbConnection, CommandType commandType, string commandText, OleDbParameter[] p, out string msg, bool setMsg)
    {
        msg = "";
        //設置命令
        OleDbCommand dbCommand = new OleDbCommand();
        dbCommand.Connection = dbConnection;
        dbCommand.CommandType = commandType;
        dbCommand.CommandText = commandText;
        //設置參數
        if (p != null)
        {
            foreach (OleDbParameter pi in p)
            {
                dbCommand.Parameters.Add(pi);
            }
        }
        //讀取第一個結果集
        OleDbDataReader dbReader = null;
        try
        {
            dbReader = dbCommand.ExecuteReader();
        }
        catch (InvalidOperationException eo)
        {
            msg = "讀取數據失敗:" + eo.Message.Replace("/n", "").Replace("/r", "") + "//n";
            if (setMsg)
            {
                SetMsgJS(aPage.Master, msg);
            }
        }
        catch (OleDbException ex)
        {
            msg = "讀取數據失敗:" + ex.Message.Replace("/n", "").Replace("/r", "") + "//n";
            if (setMsg)
            {
                SetMsgJS(aPage.Master, msg);
            }
        }
        return dbReader;
    }
    #endregion

   

#region 執行sql命令或存儲過程
    public int execCommand(Page aPage, OleDbConnection dbConnection, CommandType commandType, string commandText, OleDbParameter[] p, out string msg, bool setMsg)
    {
        bool needCloseDB = false;
        int row = 0;
        msg = "";
        //創建並設置SqlConnection
        if (dbConnection == null)
        {
            needCloseDB = true;
            dbConnection = OpenConnect(aPage, setMsg);
            if (dbConnection == null) return -1;
        }
        //創建並設置SqlCommand
        OleDbCommand dbCommand = new OleDbCommand();
        dbCommand.Connection = dbConnection;
        dbCommand.CommandType = commandType;
        dbCommand.CommandText = commandText;
        //設置參數
        if (p != null)
        {
            foreach (OleDbParameter pi in p)
            {
                dbCommand.Parameters.Add(pi);
            }
        }
        //執行命令
        try
        {
            row = dbCommand.ExecuteNonQuery();
        }
        catch (InvalidOperationException eo)
        {
            msg = eo.Message.Replace("/n", "").Replace("/r", "") + "//n";
            if (setMsg)
            {
                SetMsgJS(aPage.Master, msg);
            }
            row = -1;
        }
        catch (OleDbException ex)
        {
            //執行過程出錯
            msg = ex.Message.Replace("/n", "").Replace("/r", "") + "//n";
            if (setMsg)
            {
                SetMsgJS(aPage.Master, msg);
            }
            row = -1;
        }
        //關閉數據庫
        if (needCloseDB)
        {
            CloseConnect(dbConnection);
        }
        return row;
    }
    #endregion

上面的方法都用到一個SetMsgJS方法,這個方法是用來給母版頁設置信息的

public static void SetMsgJS(MasterPage masterPage, string msg)
    {
        Literal lt = (Literal)masterPage.FindControl("LiteralMsg");
        if (lt != null)
        {
            lt.Text += msg;
        }
    }

在母版頁裏定義是這樣子的:
   

<script type="text/javascript">
        var msg = "";
        msg = "<asp:Literal ID="LiteralMsg" runat="server"></asp:Literal>";
        if(msg != "")
        {
            alert(msg);
        }
    </script>
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