C# 从 excel 加载数据适配器，是否有最大列数？

Question

I'm running into an issue trying to create ac# data table from an excel spreadsheet. The code is simple but for some reason when I step through it, the data table only loads with 256 of the 700 columns that are in the spreadsheet. Looking at the code below, Settings.Excel_Proj_Select is just "Select * from Project_Data$". Is there a maximum column count and if so, is there a way around this to get the full sheet into a data table?

        public static DataTable getRowData()
        {

        OleDbConnection cnn = new OleDbConnection(Settings.ExcelCN);
        OleDbCommand oconn = new OleDbCommand(Settings.Excel_Proj_Select, cnn);
        cnn.Open();
        OleDbDataAdapter adp = new OleDbDataAdapter(oconn);
        DataTable dt = new DataTable();
        adp.Fill(dt);
        cnn.Close();

        dt.Columns.Add("Extract_Date", typeof(string));
        foreach (DataRow row in dt.Rows)
        {
            row["Extract_Date"] = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss");
        }

        return dt;
    }

Any info is appreciated. Thank you!

Answer 1

There appears to be a 255 max number of columns when using the Ole provider for this, yes.

But you can use a simple workaround by specifying the range in your queries:

//Modify the range to suit your needs
SELECT * FROM Project_Data$[RANGE]:[HERE]

You can then run multiple queries, each which SELECT different ranges, then combine the data.

Please see here for another method using OpenXML.