[C#自學第一天] Excel的讀取和寫入

在ERP定製開發的過程中，很多操作都是和Excel相關的,主要就是學習一些Excel處理的方法, 從而熟悉且靈活使用它。

1)  使用DataReader循環讀取Excel某列的數據:

protected void Button1_Click(object sender, EventArgs e)
{
    string connectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\temp\WebSite8\App_Data\Book1.xls;Extended Properties=""Excel 8.0;HDR=YES;""";  //定義excel的路徑，可以使用完整文件名;
    DbProviderFactory factory = DbProviderFactories.GetFactory("System.Data.OleDb"); //使用他的原因就是對類進行抽象; 具體原理還不是很清楚，使用DbProviderFactory必須引用System.Data.Common;

    using (DbConnection connection = factory.CreateConnection())  //定義connection 對象
    {
        connection.ConnectionString = connectionString;     //定義連接; 使用DBconnection的ConnectionString屬性;

        using (DbCommand command = connection.CreateCommand())   //定義DbCommand對象;
        {
            // Cities$ comes from the name of the worksheet
            command.CommandText = "SELECT ID,City,State FROM [Cities$]"; //定義commandText;

            connection.Open();

            using (DbDataReader dr = command.ExecuteReader())   //定義DbDataReader對象, 通過dr.Read()屬性判斷結束，來遍歷所有列的值;
            {
                while (dr.Read())
                {
                    Response.Write(dr["ID"].ToString());
                    //Response.Write(dr[2].ToString());    //當然也可以通過直接指定第幾列來取具體的值;
                }
            }
        }
    }
}

 2)  以數據庫訪問的方式，把Excel的數據以放在gridview中顯示:

 

protected void Button2_Click(object sender, EventArgs e)
{
    string connectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\temp\WebSite8\App_Data\Book1.xls;Extended Properties=""Excel 8.0;HDR=YES;""";
    try
    {
        string sql ="SELECT * FROM [Cities$]" ;
        OleDbConnection OleConn = new OleDbConnection(connectionString);  //使用OleDbConnection需要引用"using System.Data.OleDb";
        OleConn.Open();

        OleDbDataAdapter OleDaExcel = new OleDbDataAdapter(sql, OleConn); //OleDataAdapter和SqlDataAdapter功能類似;
        DataSet OleDs = new DataSet();
        OleDaExcel.Fill(OleDs,"Cities");
        OleConn.Close();
        GridView1.DataSource = OleDs;
        GridView1.DataBind();

    }
    catch (Exception ex)
    {
        Response.Write("Fail to bind excel: "+ex.Message);
    }
}

 3) 把數據庫裏面的內容同步到Excel中: 使用Microsoft.Office.Interop.Excel.Application，裏面有清楚的Workbook和Worksheet的定義:

 

protected void Button3_Click(object sender, EventArgs e)
    {
        //添加組件,COM裏面的：Microsoft Excel 11.0 Object Library
        Microsoft.Office.Interop.Excel.Application app = new Microsoft.Office.Interop.Excel.ApplicationClass();
        System.Data.DataTable excelTable = new System.Data.DataTable();

        SqlConnection sqlconn = new SqlConnection("Data Source=efacsdb;Initial Catalog=whatifdb;User ID=sa; Password=L-BBgD7q");
        sqlconn.Open();
        SqlDataAdapter sda = new SqlDataAdapter("select top 10 * from t_tt_buyer_group", sqlconn);
        DataSet ds = new DataSet();
        sda.Fill(ds,"table1");
        excelTable = ds.Tables["table1"];

        string filePath ="c:\temp\test.xls";
        try
        {
            app.Visible = false;
            Workbook wb = app.Workbooks.Add(true);
            Worksheet ws = app.Worksheets[1] as Worksheet;
            if (excelTable.Rows.Count > 0)
            {
                int row = 0;
                row = excelTable.Rows.Count;
                int col = excelTable.Columns.Count;
                for (int i= 0; i<row; i++)
                {
                    for (int j=0; j<col; j++)
                    {
                        string str = excelTable.Rows[i][j].ToString();
                        ws.Cells[i+2,j+1] = str;
                    }
                }
            }

            int size = excelTable.Columns.Count;
            for (int i=0;i< size;i++)
            {
               ws.Cells[1,1+i] = excelTable.Columns[i].ColumnName;
            }
            //不顯示保存和覆蓋的確認提示框:
            app.DisplayAlerts = false;
            app.AlertBeforeOverwriting = false;
            //保存工作簿
            wb.SaveCopyAs(@"C:\temp\test1.xls");  \\如果用wb.save()就會報錯，提示Sheet1.xls無法訪問; 保存時如果文件不存在也會報錯;
            //保存excel文件
            //app.SaveWorkspace(filePath);
            app.Quit();
            app=null;
        }
        catch (Exception ex)
        {
            Response.Write("export error"+ex.Message);
        }
    }