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Update :Result is not transfered to the orginal dataset. Sorting Rows in Dataset using C#

Update: even though I have got the required result but when the the second function access the data table the value is still the same
It a sequential program with two functions in different classes. First sort and second replace function. So it should sort the value and other function should be able to retrieve the sorted table but when it retrieve the datatable it gives the unsorted table.
I have used acceptchanges() but it also give the same result.
The program is trying to sort the table according to the required field and the result is stored in Sorted table variable. I am trying to copy this to the original i-e sourceTables but it is not working and is adding another row instead of updating [As shown in below dig]. I have tried to copy whole table but it does not work and by adding rows it is not giving the required result. I have used different methods but I am not getting the required result.
List<DataTable> sourceTables = context.GetDataByTable(sourceTable.StringValue);
List<DataTable> targetTables = context.GetDataByTable(targetTable.StringValue, sourceTables.Count);
string orderDesc= orderField.StringValue + " DESC";
for (int i = 0; i < sourceTables.Count; i++)
{
DataView dv = sourceTables[i].DefaultView;
if (orderDirection.StringValue == OrderDirectionAsc)
{
// for Sorting in Ascending Order
dv.Sort = orderField.StringValue;
}
else
{
// for Sorting in Descending Order
dv.Sort = orderDesc;
}
DataTable sortedTable = dv.ToTable();
DataTable dttableNew = sortedTable.Clone();
//sourceTables[i] = sortedTable.Copy();
//targetTables[i] = dv.ToTable();
//targetTables[i] = sortedTable.Copy();
// foreach (DataRow dr in sortedTable.Rows)
//// targetTables[i].Rows.Add(dr.ItemArray);
//}
for (int j = 0; j < sourceTables[i].Rows.Count; j++)
{
if (sourceTable.GetValue().ToString() == targetTable.GetValue().ToString())
{
foreach (DataRow dr in sortedTable.Rows)
{
targetTables[i].Rows.Add(dr.ItemArray);
}
else
{
foreach (DataRow dr in sortedTable.Rows)
{
targetTables[i].Rows.Add(dr.ItemArray);
}
// targetTables[i] = sortedTable.Copy(); does not work
//foreach (DataRow drtableOld in sortedTable.Rows)
//{
// targetTables[i].ImportRow(drtableOld);
//}
Instead of replacing the first values it is adding more rows
any help would be appreciated

If any one have problem with duplicate data or the changes are only local and is not effecting the original data table. Remember to always use .ImportRow(dr) function to add rows to the table and if you use Tables[i].Rows.Add(dr.ItemArray); the changes will affect only the local table and not the original one. Use .clear to remove the old rows from the orginal table. The action done directly on the original function will only effect the rows. If it is done on the clone copy changes will nor affect the original table.
Here is the complete code
DataTable sortTable = dv.ToTable();
if (sTable.GetValue().ToString() == tTable.GetValue().ToString())
{
sTables[i].Clear();
foreach (DataRow dr in sortTable.Rows)
{
sTables[i].ImportRow(dr);
}
sTables[i].AcceptChanges();
}

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.

making rows distinct and showing all the columns

In my project there are two datatables dtFail and dtFailed (dtFailed has nothing but column names declarations). dtFail has duplicate "EmployeeName" column values. so i took a dataview dvFail and did the process to make them distinct as shown in the below code:
dtFail
I tried the below code:
DataView dvFail = new DataView(dtFail);
dtFail = dvFail.ToTable(true, "EmployeeName"); //showing only one column in dtFail
dtFailed (only one column)
If i do like below
DataView dvFail = new DataView(dtFail);
dtFail = dvFail.ToTable(true, "EmployeeName","EmployeeRole","Status");
dtFailed (showing but with duplicate rows)
Then the datatable dtFailed is storing duplicate "EmployeeName" also.
Please Help
Thanks in Advance.

Try this query-
DataTable distinctTable = originalTable.DefaultView.ToTable( /*distinct*/ true);
For more info hit below link-
https://social.msdn.microsoft.com/Forums/en-US/ed9c6a6a-a93e-4bf5-a892-d8471b84aa3b/distinct-in-datatable-or-dataview?forum=adodotnetdataset
I hope this would have helped you.

SOLUTION 1:
Based on the question my understanding is, we need to consider duplicates based on EmployeeName and we need not worry about other columns. If that is the case below solution works better.
foreach(DataRow r in dtFail.AsEnumerable())
{
if (!dt1.AsEnumerable().Any(r1 => r1["EmployeeName"] == r["EmployeeName"]))
{
// if you don't want to copy entire row create new DataRow
// with required fields and add that row.
dt1.Rows.Add(r.ItemArray);
}
}
if you want you can put dt1 back to dtFail.
SOLUTION 2:
If we need to consider distinct rows I prefer below solution.
var temp = dtFail.AsEnumerable().Distinct();
dtFail = temp.CopyToDataTable();

I'm not sure it will be helpful or not. As far as I get from your question that you want EmployeeName to be distinct irrelevant to other columns. But if you do ToTable and turn on the distinct flag it will give all the distinct rows, doesn't matter how many columns are involved there. So if you mention only EmployeeName it will obviously give you distinct EmployeeNames, not all the columns associated with it.
So, thats what I did, initially select only the distinct EmployeeName columns and put it into a temp DataTable dtt.
DataTable dtt = dvFail.DefaultView.ToTable(true, "EmployeeName");
Secondly I've created another temp DataTable where we put the segregated rows from the main DataTable dtFail and set the column names manually.
DataTable TempDataTable = new DataTable();
DataTable dtFailed = new DataTable();
Prepare the columns in the dtFailed DataTable.
if (dtFailed.Columns.Count == 0)
{
dtFailed.Columns.Add("EmployeeName");
dtFailed.Columns.Add("EmployeeRole");
dtFailed.Columns.Add("Status");
dtFailed.Columns.Add("Date");
}
Loop through the distinct EmployeeName dtt DataTable and match the EmployeeName and keep that selected first row in the TempDataTable. Finally all rows transferred into the dtFailed.
for (int j = 0; j < dtt.Rows.Count; j++)
{
string EmployeeName = dtt.Rows[j]["EmployeeName"].ToString();
TempDataTable = dvFail.Select("EmployeeName = " + EmployeeName).CopyToDataTable();
dtFailed.Rows.Add(TempDataTable.Rows[0].ItemArray);
}

Delete row from datatable where first column does not contain (some string)

I have DataTable with the following columns:
ClientID date numberOfTransactions price
ClientID is of type string and I need to ensure that its contents include "A-" and "N6" for every value in the table.
I need to delete all rows from the DataTable where this first column (ClientID) does not contain both "A-" and "N6" (some totals and other unnecessary data). How can I select and delete these rows specifically from the DataTable?
I know this:
foreach (DataRow row in table.Rows) // Loop over the rows.
{
//Here should come part "if first column contains mentioned values
}
I also know this
If (string.Contains("A-") == true && string.Contains("N6") == true)
{
//Do something
}
I need help how to implement this for first column of each row.

Try this:
EDIT: Totally messed up that last line, so if you tried it, try it now that I made it not stupid. =)
List<int> IndicesToRemove = new List<int>();
DataTable table = new DataTable(); //Obviously, your table will already exist at this point
foreach (DataRow row in table.Rows)
{
if (!(row["ClientID"].ToString().Contains("A-") && row["ClientID"].ToString().Contains("N6")))
IndicesToRemove.Add(table.Rows.IndexOf(row));
}
IndicesToRemove.Sort();
for (int i = IndicesToRemove.Count - 1; i >= 0; i--) table.Rows.RemoveAt(IndicesToRemove[i]);

try using this,
assuming dt as your Datatabe object and ClientID as your first column (hence using ItemArray[0])
for(int i=0; i<dt.Rows.Count; i++)
{
temp = dt.Rows[i].ItemArray[0].ToString();
if (System.Text.RegularExpressions.Regex.IsMatch(temp, "A-", System.Text.RegularExpressions.RegexOptions.IgnoreCase) || System.Text.RegularExpressions.Regex.IsMatch(temp, "N6", System.Text.RegularExpressions.RegexOptions.IgnoreCase))
{
dt.Rows.RemoveAt(i);
i--;
}
}
Simple and straight forward solution... hope it helps

this should be more efficient, both in lines of Code and Time, try this :)
for(int x=0; x<table.Rows.Count;)
{
if (!table.Rows[x].ItemArray[0].contains("A-") && !table.Rows[x].ItemArray[0].contains("N6"))
table.Rows.RemoveAt(x);
else x++;
}
Happy Coding

Preface: C.Barlow's existing answer is awesome, this is just another route someone could take.
This is one way to do it where you never have to loop all the way through the original table (by taking advantage of the DataTable.Select() method):
DataTable table = new DataTable(); // This would be your existing DataTable
// Grab only the rows that meet your criteria using the .Select() method
DataRow[] newRows = table.Select("ClientID LIKE '%A-%' AND ClientID LIKE '%N6%'");
// Create a new table with the same schema as your existing one.
DataTable newTable = table.Clone();
foreach (DataRow r in newRows)
{
// Dump the selected rows into the table.
newTable.LoadDataRow(r.ItemArray, true);
}
And now you have a DataTable with only the rows you want. If necessary, at this point you could clear out the original table and replace it with the contents of the new one:
table.Clear();
table = newTable.Copy();
Edit: I thought of a memory optimization last night, you can just overwrite the existing table once you have the rows you need, which avoids the need for the temporary table.
DataTable table = new DataTable(); // This would be your existing DataTable
// Grab only the rows that meet your criteria using the .Select() method
DataRow[] newRows = table.Select("ClientID LIKE '%A-%' AND ClientID LIKE '%N6%'");
// Clear out the old table
table.Clear();
foreach (DataRow r in newRows)
{
// Dump the selected rows into the table.
table.LoadDataRow(r.ItemArray, true);
}

Copy rows from one Datatable to another DataTable?

How can I copy specific rows from DataTable to another Datable in c#? There will be more than one row.

foreach (DataRow dr in dataTable1.Rows) {
if (/* some condition */)
dataTable2.Rows.Add(dr.ItemArray);
}
The above example assumes that dataTable1 and dataTable2 have the same number, type and order of columns.

Copy Specified Rows from Table to another
// here dttablenew is a new Table and dttableOld is table Which having the data
dttableNew = dttableOld.Clone();
foreach (DataRow drtableOld in dttableOld.Rows)
{
if (/*put some Condition */)
{
dtTableNew.ImportRow(drtableOld);
}
}

Try This
String matchString="ID0001"//assuming we have to find rows having key=ID0001
DataTable dtTarget = new DataTable();
dtTarget = dtSource.Clone();
DataRow[] rowsToCopy;
rowsToCopy = dtSource.Select("key='" + matchString + "'");
foreach (DataRow temp in rowsToCopy)
{
dtTarget.ImportRow(temp);
}

Check this out, you may like it (previously, please, clone table1 to table2):
table1.AsEnumerable().Take(recodCount).CopyToDataTable(table2,LoadOption.OverwriteChanges);
Or:
table1.AsEnumerable().Where ( yourcondition ) .CopyToDataTable(table2,LoadOption.OverwriteChanges);

Supported in: 4, 3.5 SP1, you can now just call a method on the object.
DataTable dataTable2 = dataTable1.Copy()

As a result of the other posts, this is the shortest I could get:
DataTable destTable = sourceTable.Clone();
sourceTable.AsEnumerable().Where(row => /* condition */ ).ToList().ForEach(row => destTable.ImportRow(row));

I've created an easy way to do this issue
DataTable newTable = oldtable.Clone();
for (int i = 0; i < oldtable.Rows.Count; i++)
{
DataRow drNew = newTable.NewRow();
drNew.ItemArray = oldtable.Rows[i].ItemArray;
newTable.Rows.Add(drNew);
}

I needed to copy rows from multiple tables with the same structure into a new table to be used as a datasource for datagridview:
// Generate DataTable[] alltables from multiple datatables
DataTable newTable = alltables[0].Clone();
foreach (DataTable dt in alltables)
{
for (int i = 0; i < dt.Rows.Count; i++)
newTable.Rows.Add(dt.Rows[i].ItemArray);
}

below sample would be the fastest way to copy one row.
each cell is being copied based on the column name.
in case you dont need a specific cell to copy then have a try catch or add if.
if your going to copy more than 1 row then loop the code below.
DataRow dr = dataset1.Tables[0].NewRow();
for (int i = 0; i < dataset1.Tables[1].Columns.Count; i++)
{
dr[dataset1.Tables[1].Columns[i].ColumnName] = dataset1.Tables[1].Rows[0][i];
}
datasetReport.Tables[0].Rows.Add(dr);
dataset1.Tables[1].Rows[0][i]; change the index 0 to your specified row index or you can use a variable if your going to loop or if its going to be logical

private void CopyDataTable(DataTable table){
// Create an object variable for the copy.
DataTable copyDataTable;
copyDataTable = table.Copy();
// Insert code to work with the copy.
}

To copy whole datatable just do this:
DataGridView sourceGrid = this.dataGridView1;
DataGridView targetGrid = this.dataGridView2;
targetGrid.DataSource = sourceGrid.DataSource;

For those who want single command SQL query for that:
INSERT INTO TABLE002
(COL001_MEM_ID, COL002_MEM_NAME, COL002_MEM_ADD, COL002_CREATE_USER_C, COL002_CREATE_S)
SELECT COL001_MEM_ID, COL001_MEM_NAME, COL001_MEM_ADD, COL001_CREATE_USER_C, COL001_CREATE_S
FROM TABLE001;
This query will copy data from TABLE001 to TABLE002 and we assume that both columns had different column names.
Column names are mapped one-to-one like:
COL001_MEM_ID -> COL001_MEM_ID
COL001_MEM_NAME -> COL002_MEM_NAME
COL001_MEM_ADD -> COL002_MEM_ADD
COL001_CREATE_USER_C -> COL002_CREATE_USER_C
COL002_CREATE_S -> COL002_CREATE_S
You can also specify where clause, if you need some condition.

There is better way to do this.
DataTable targetDataTable = new DataTable();
targetDataTable = changedColumnMetadata.AsEnumerable().Where(dataRow => entityName.Equals(dataRow["EntityName"])).CopyToDataTable();
Please try this and let me know in case of any issues.

You can do it calling the DataTable.Copy() method, for example:
DataSet ds = new DataSet();
System.Data.DataTable dt = new System.Data.DataTable();
dt = _BOSearchView.DS.Tables[BusLib.TPV.TableName.SearchView].Copy();
ds.Tables.Add(dt);
UltGrdSaleExcel.SetDataBinding(ds, dt.TableName, true);

use Merge, this will append all rows of newDataTable with oldDateTale
oldDateTale.Merge(newDataTable);