Develop Reference

SSIS Script Task: Select from datatable1 into datatable2

I'm using SQL 2014, Visual Studio 2013. I have the following code that's part of a larger script task:
//Load DataTable1 with Source Excel Sheet Data
OleDbCommand oconn = new OleDbCommand("select * from [" + sheetname + "]", cnn);
OleDbDataAdapter adp = new OleDbDataAdapter(oconn);
DataTable dt = new DataTable();
adp.Fill(dt);
What I would like to do next is select a targeted number of columns from datatable1, and fill another datatable. Something like this:
//Load another DataTable with Data from datatable1
OleDbCommand oconn2 = new OleDbCommand("select [column1], [column2] from datatable1", cnn);
OleDbDataAdapter adp2 = new OleDbDataAdapter(oconn2);
DataTable dt2 = new DataTable();
adp2.Fill(dt2);
Is this possible? The reason behind this is complicated, but I don't know another way around it. My source files are Excel. So the data needs to be brought into a datatable. Then the column names need to modified. Then a table can be made with the modified column names. But first, the data needs to be brought into a datatable as is, as I'm not sure I want to modify the source files.
Thank you.

Define the second DataTable using the data types and new names for the columns that will be added to it. Then you can populate this object by using the ordinal position of the columns in the initial DataTable with the Add method as below.
DataTable dt2 = new DataTable();
dt2.Columns.Add("NewColumnName1", typeof(int));
dt2.Columns.Add("NewColumnName2", typeof(string));
//in this example dt is the original DataTable
foreach (DataRow dr in dt.Rows)
{
//add only necessary columns by their
//ordinal position in source DataTable
dt2.Rows.Add(dr[1], dr[0]);
}

How to Create sub DataTable from an existing DataTable

I have a DataTable(dataTable1) that have 25-30 columns. I want to bind a DataGridView by creating a small DataTable (dataTable2) that will have few columns (may 5-10) from the existing DataTable.
So my main task is to create a DataTable with fewer columns from the existing one.
Here is the code what I have tried so for..
DataTable subDataTable()
{
DataTable smallTable=new DataTable();
smallTable =dataTable1;// dataTable1 is already filled with data
smallTable.Columns.Remove("Column2");
smallTable.Columns.Remove("Column5");
smallTable.Columns.Remove("Column6");
smallTable.Columns.Remove("Column13");
smallTable.Columns.Remove("Column16");
return smallTable;
}
Its working fine. But I'm looking if there any better way.

You can try to convert your DataTable to IEnumerable,and Select necessary fields with linq like this:
var myValues = dataTable1.AsEnumerable()
.Select(x => new { col1 = x["Column1"], col2 = x["Column2"]..});
dataGridView.DataSource = myValues;

Your code will not work because you all you do is assign a variable smallTable with reference to dataTable1 and you removing columns from your original table object
Linq is faster to write but here is what you want to do to understand your issue:
DataTable smallTable = dataTable1.Clone(); // Copy data structure
// Now you can remove your columns
smallTable.Columns.Remove("Column2");
......
foreach (var row in dataTable1.Rows) // iterate all rows
{
var newRow = smallTable.NewRow();
foreach (var col in smallTable.Columns) // and iterate only needed columns
{
newRow[col.ColumnName] = row[col.ColumnName];
}
}
This is pretty much what sugar-coated by Linq

DataView dv = new DataView(dataTable1);
DataTable smallTable = dv.ToTable(true, new string[] { "Column2", "Column5"...});
https://social.msdn.microsoft.com/Forums/en-US/ac2c7c95-66d6-4db6-a6fb-4dccd5fa701e/is-there-a-better-way-to-get-subtable-with-selected-columns-of-a-datatable?forum=adodotnetdataset
Tomer.

Selecting specific columns from a dataTable and copy it to another DataTable

I have a DataTable Dt1 and another DataTable Dt2.
Dt1 contains many columns and rows and Dt2 is basically empty
I know I should use Dt1.Select to select the specific DataTaRow [] but how can I copy them to Dt2
DataRow [] row = Dt1.Select("ID,MIN_VALUE,MAX_VALUE");
how can i copy them to Dt2?

For .Net Framework 3.5+
You can use CopyToDataTable method.
Returns a DataTable that contains copies of the DataRow objects, given
an input IEnumerable object.
DataTable dt1 = new DataTable();
DataRow[] dr = dt.Select("Your string");
DataTable dt2 = dr.CopyToDataTable();

Adding data to a row in a Dataset?

I am trying to add data to a row in a dataset but the data is always on a new row?
I need the data to populate under its column. I need something like Ds.Tables[0].Rows[1].add("Item")
This is how i am inserting the data:
DataSet ds = new DataSet();
ds.Tables.Add("Properties");
//GPS
ds.Tables[0].Columns.Add(ArrayProperties[0].FormMobiField);
ds.Tables[0].Rows.Add(ArrayProperties[0].Value);
//Street Num and Name
ds.Tables[0].Columns.Add(ArrayProperties[3].FormMobiField);
ds.Tables[0].Rows.Add(ArrayProperties[3].Value);
//Suburb
ds.Tables[0].Columns.Add(ArrayProperties[6].FormMobiField);
ds.Tables[0].Rows.Add(ArrayProperties[6].Value);
//City
ds.Tables[0].Columns.Add(ArrayProperties[7].FormMobiField);
ds.Tables[0].Rows.Add(ArrayProperties[7].Value);
//Province
ds.Tables[0].Columns.Add(ArrayProperties[8].FormMobiField);
ds.Tables[0].Rows.Add(ArrayProperties[8].Value);
//Locality Map
ds.Tables[0].Columns.Add(ArrayProperties[9].FormMobiField);
ds.Tables[0].Rows.Add(ArrayProperties[9].Value);
//Property Type
ds.Tables[0].Columns.Add(ArrayProperties[10].FormMobiField);
ds.Tables[0].Rows.Add(ArrayProperties[10].Value);

Just get a new Row from the DataTable and then add that row to the table, Use DataTable.NewRow method
DataRow dr = ds.Tables[0].NewRow();
dr["Column1"] = "value";
dr["Column2"] = "value";
dr["Column3"] = "value";
ds.Tables[0].Rows.Add(dr);
You are adding row after adding each column, You may first create your data table's structure by adding all the columns and then you can get the new row using DataTable.NewRow() and later you can add that row to your data table. After adding all the columns you may also try:
ds.Tables[0].Rows.Add(ArrayProperties[0].Value,ArrayProperties[1].Value,ArrayProperties[2].Value,ArrayProperties[3].Value);

The columns collection of a Datatable regards the table structure. In your code you mix adding columns and populating fileds.
You should first create the structure (not tested and syntax errors can occur):
Dataset ds = new Dataset();
Datatable dt = new Datatable();
dt.columns.add(new Column.add(...));
...
dt.columns.add(new Column.add(...));
ds.Tables.add(dt);
And then:
Datarow r = ds.tables[0].NewRow();
r["column1"] = value1;
...
r["columnX"] = valueX;
ds.Tables[0].rows.add(r);
See this msdn article for more details.

Add the columns as you are adding. For populating rows, do the below.
foreach (DataRow row in ds.Tables[0]) // Loop over the rows.
{
row[ArrayProperties[i].FormMobiField]=ArrayProperties[0].Value;
i++;
}
If it doesn't work then let me know,

How to remove the merged datatable from the datatable using C#.Net?

I have two datatables D1 and D2.
I merged the datatable D2 with D1 as follows:
D1.Merge(D2);
But now, I want to remove the DataTable D2 from the D1. How to achieve this?

This may not be the most beautiful solution, but you can consider adding a distinctive column to your tables. I set those values by hand, but for example if your datatables are filled from a SQL query, you can easily add that distinctive column in those queries and use them accordingly.
D1.Columns.Add("ORIGINAL_DATATABLE_NAME", typeof(int));
D2.Columns.Add("ORIGINAL_DATATABLE_NAME", typeof(int));
foreach(DataRow row in D1.Rows)
row["ORIGINAL_DATATABLE_NAME"] = 1;
foreach(DataRow row in D2.Rows)
row["ORIGINAL_DATATABLE_NAME"] = 2;
D1.Merge(D2);
DataRow[] rows = D1.Select("ORIGINAL_DATATABLE_NAME=1", "");
DataSet ds = new DataSet();
ds.Merge(rows, false, MissingSchemaAction.Add);
ds.Tables[0].Columns.Remove("ORIGINAL_DATATABLE_NAME");