C＃将一个数据表拆分为多个数据集

Question

I have correct source DataTable "sourceDataTable" and I call method to split it into several and store the result into DataSet "ds":

 DataSet ds = MyClass.SplitDataTables(sourceDataTable);

Here is the method MyClass.SplitDataTables():

public static DataSet SplitDataTables(DataTable sourceDataTable)
    {
        using (DataSet dsOut = new DataSet())
        {
            DataTable dt1 = new DataTable;
            DataTable dt2 = new DataTable;
            DataTable dt3 = new DataTable;

            dt1 = sourceDataTable.Clone();
            dt2 = sourceDataTable.Clone();
            dt3 = sourceDataTable.Clone();

            foreach (DataRow row in sourceDataTable.Rows)
            {
                //column is for example "City" and some row has "Boston" in it, so I put this row into dt1
                if (row["ColumnName"].ToString() == "something")
                {
                    dt1.ImportRow(row);
                }
                else if (...)
                {  } //for other DataTables dt2, dt3, etc...

                else .......... ;
            }


            //here I put resulting DataTables into one DataSet which is returned
            string[] cols= { "dt1", "dt2", "dt3" };

            foreach (string col in cols)
            {
                dsOut.Tables.Add(col);
            }

            return dsOut;

        }
    }

So with this returned DataSet I display new Windows each with one DataTable

foreach (DataTable dtt in ds.Tables)
                    {
                        string msg = dtt.TableName;
                        Window2 win2 = new Window2(dtt, msg);
                        win2.Show();
                    }

All I get shown is Windows with placeholder for "empty DataGrid" Windows code is correct, as it works whith "unsplit DataTable".

I assume code in splitting DataTables is all wrong as it does not output DataSet with filled DataTables. I will greatly appreciate any help on this issue. Thank you!

Answer 1

You don't need a for loop here

Replace below code

string[] cols= { "dt1", "dt2", "dt3" };

foreach (string col in cols)
   {
     dsOut.Tables.Add(col);
   }

With this

dsOut.Tables.Add(dt1);
dsOut.Tables.Add(dt2);
dsOut.Tables.Add(dt3);

Answer 2

Thanks to @Krishna I got this solved. So if you ever encounter similar problem here are 2 things to note:

string[] cols = { "dt1", "dt2", "dt3", ... };

            foreach (string col in cols)
            {
                dsOut.Tables.Add(col);
            }

This cycle does not have access to objects of DataTables with same name and writes only empty DataTables into DataSet collection (regardless of same name!).

If you create new DataTable and you will be making it a clone of another DataTable, dont bother yet with setting its name.

DataTable dt1 = new DataTable();

Make new DataTable of same format as source DataTable:

dt1 = sourceDataTable.Clone();
dt2 = sourceDataTable.Clone();
//etc...

Now you have to set unique DataTable names to each DataTable cloned from source DataTable:

dt1.TableName = "Name1";
dt2.TableName = "Name2";
//and so on

Now all works as intended.