Develop Reference

Foreach row in datatable1 store in datatable2

I am trying to do a foreach loop that stores each row from datatable1 into datatable2, so foreach row in datatable1 store the row in datatable2, this is what I have so far:
public static DataTable datatable2 = new DataTable();
public void createDatatable()
{
profile p = new profile();
DataTable datatable1 = p.getResults(System.Convert.ToInt32(HttpContext.Current.Session["ID"]));
foreach (DataRow dr in datatable1.Rows)
{
datatable2 = datatable1.Copy();
}
}
This just copies the columns too which I don't want, I just want each row stored from datatable2 into datatable1

I assume dataTable1 & dataTable2 has same schema (same number of columns with similar datatype). Don't use .Copy(). Use Rows.Add to copy content as follows,
foreach (DataRow dr in dataTable1.Rows) {
dataTable2.Rows.Add(dr.ItemArray);
}

Checking value in column foreach row

The DataTable (dt) stores the retrieved values of carID's and makes so it stores like 3 rows within the DataTable, I also have another DataTable called dt2 which also stores carID's and makes, I am trying to loop through each row in the dt to see if any carID stored in the dt exists in any of the rows in dt2, here is what I have so far:
DataTable dt = w.getUserCars(userID);
foreach (DataRow dr in dt.Rows)
{
string carID = dr["carID"].ToString();
}
How do I do this?

You should be able to achieve this using DataTable.Select() method. You are on the right track. You just need to add the method to find the Row(s) in dt2.
DataTable dt = w.getUserCars(userID);
DataRow[] foundRows;
foreach (DataRow dr in dt.Rows)
{
string carID = dr["carID"].ToString();
foundRows = dt2.Select("carID = " + carID);
// do stuff here with foundRows
foreach (DataRow r in foundRows)
{
r.Delete();
}
}

Delete Row From Data Table

I want to Delete the Multiple records from the DataTable
For example :
in my case PaperId is Repeating several Times.I want to Delete it all Duplicate records.
i have written code but loop is giving error
DataSet ds = new DataSet();
sqlDad.Fill(ds);
DataTable dt1 = new DataTable();
ds.Tables.Add(dt1);
dt1 = ds.Tables[0];
DataTable dt2 = new DataTable();
dt2 = dt1;
List<DataRow> rowsToDelete = new List<DataRow>();
foreach(DataRow dr in ds.Tables[0].Rows)
{
int r = ds.Tables[0].Columns.Count;
string x = dr.ItemArray[0].ToString();
int counter = 0;
foreach (DataRow dr1 in ds.Tables[0].Rows)
{
if (x == dr1.ItemArray[0].ToString())
{
counter++;
}
if (counter > 1)
{
rowsToDelete.Add(dr1);
foreach (DataRow row in rowsToDelete)
{
dt2.Rows.Remove(row);
}
dt2.AcceptChanges();
rowsToDelete.Clear();
}
}

Using the DefaultView of the DataTable and setting the sort order on the column that you don't want repeats to appear. You could loop over the rows and delete all the rows after the first one
// Work on the first table of the DataSet
DataTable dt1 = ds.Tables[0];
// No need to work if we have only 0 or 1 rows
if(dt1.Rows.Count <= 1)
return;
// Setting the sort order on the desidered column
dt1.DefaultView.Sort = dt1.Columns[0].ColumnName;
// Set an initial value ( I choose an empty string but you could set to something not possible here
string x = string.Empty;
// Loop over the row in sorted order
foreach(DataRowView dr in dt1.DefaultView)
{
// If we have a new value, keep it else delete the row
if(x != dr[0].ToString())
x = dr[0].ToString();
else
dr.Row.Delete();
}
// Finale step, remove the deleted rows
dt1.AcceptChanges();

Try This
DataRow[] rows;
rows=dataTable.Select("UserName = 'ABC'"); // UserName is Column Name
foreach(DataRow r in rows)
r.Delete();

If you want to remove the entire row from DataTable ,
try this
DataTable dt = new DataTable(); //User DataTable
DataRow[] rows;
rows = dt.Select("UserName = 'KarthiK'");
foreach (DataRow row in rows)
dt.Rows.Remove(row);

Looping through a DataTable

Well. I have a DataTable with multiple columns and multiple rows.
I want to loop through the DataTable dynamically basically the output should look as follows excluding the braces :
Name (DataColumn)
Tom (DataRow)
Peter (DataRow)
Surname (DataColumn)
Smith (DataRow)
Brown (DataRow)
foreach (DataColumn col in rightsTable.Columns)
{
foreach (DataRow row in rightsTable.Rows)
{
//output
}
}
I typed that out and noticed this would not work. Can someone please advice on a better way of doing this?

foreach (DataColumn col in rightsTable.Columns)
{
foreach (DataRow row in rightsTable.Rows)
{
Console.WriteLine(row[col.ColumnName].ToString());
}
}

foreach (DataRow row in dt.Rows)
{
foreach (DataColumn col in dt.Columns)
Console.WriteLine(row[col]);
}

Please try the following code below:
//Here I am using a reader object to fetch data from database, along with sqlcommand onject (cmd).
//Once the data is loaded to the Datatable object (datatable) you can loop through it using the datatable.rows.count prop.
using (reader = cmd.ExecuteReader())
{
// Load the Data table object
dataTable.Load(reader);
if (dataTable.Rows.Count > 0)
{
DataColumn col = dataTable.Columns["YourColumnName"];
foreach (DataRow row in dataTable.Rows)
{
strJsonData = row[col].ToString();
}
}
}

If you want to change the contents of each and every cell in a datatable then we need to Create another Datatable and bind it as follows using "Import Row". If we don't create another table it will throw an Exception saying "Collection was Modified".
Consider the following code.
//New Datatable created which will have updated cells
DataTable dtUpdated = new DataTable();
//This gives similar schema to the new datatable
dtUpdated = dtReports.Clone();
foreach (DataRow row in dtReports.Rows)
{
for (int i = 0; i < dtReports.Columns.Count; i++)
{
string oldVal = row[i].ToString();
string newVal = "{"+oldVal;
row[i] = newVal;
}
dtUpdated.ImportRow(row);
}
This will have all the cells preceding with Paranthesis({)

Read from Dataset

I need to read value of the dataset.
This dataset return many rows. and each rows have single value (Customer_Name)

If you have one table in dataset and that table has one column you could do it like this:
foreach (DataRow row in dataSet.Tables[0].Rows)
{
string result = row[0].ToString();
}
Or:
foreach (DataRow row in dataSet.Tables["tablename"].Rows)
{
string result = row["columnname"].ToString();
}