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Change order of rows in DataTable in C#

Is it possible to change order of rows in DataTable so for example the one with current index of 5 moves to place with index of 3, etc.?
I have this legacy, messy code where dropdown menu get it's values from DataTable, which get it's values from database. It is impossible to make changes in database, since it has too many columns and entries. My original though was to add new column in db and order by it's values, but this is going to be hard.
So since this is only matter of presentation to user I was thinking to just switch order of rows in that DataTable. Does someone knows the best way to do this in C#?
This is my current code:
DataTable result = flokkurDao.GetMCCHABAKflokka("MSCODE");
foreach (DataRow row in result.Rows)
{
m_cboReasonCode.Properties.Items.Add(row["FLOKKUR"].ToString().Trim() + " - " + row["SKYRING"]);
}
For example I want to push row 2011 - Credit previously issued to the top of the DataTable.
SOLUTION:
For those who might have problems with ordering rows in DataTable and working with obsolete technology that doesn't supports Linq this might help:
DataRow firstSelectedRow = result.Rows[6];
DataRow firstNewRow = result.NewRow();
firstNewRow.ItemArray = firstSelectedRow.ItemArray; // copy data
result.Rows.Remove(firstSelectedRow);
result.Rows.InsertAt(firstNewRow, 0);
You have to clone row, remove it and insert it again with a new index. This code moves row with index 6 to first place in the DataTable.

If you really want randomness you could use Guid.NewGuid in LINQ's OrderBy:
DataTable result = flokkurDao.GetMCCHABAKflokka("MSCODE");
var randomOrder = result.AsEnumerable().OrderBy(r => Guid.NewGuid());
foreach (DataRow row in randomOrder)
{
// ...
}
If you actually don't want randomness but you want specific values at the top, you can use:
var orderFlokkur2011 = result.AsEnumerable()
.OrderBy(r => r.Field<int>("FLOKKUR") == 2011 ? 0 : 1);

You can use linq to order rows:
DataTable result = flokkurDao.GetMCCHABAKflokka("MSCODE");
foreach (DataRow row in result.Rows.OrderBy(x => x.ColumnName))
{
m_cboReasonCode.Properties.Items.Add(row["FLOKKUR"].ToString().Trim() + " - " + row["SKYRING"]);
}
To order by multiple columns:
result.Rows.OrderBy(x => x.ColumnName).ThenBy(x => x.OtherColumnName).ThenBy(x.YetAnotherOne)
To order by a specific value:
result.Rows.OrderBy(x => (x.ColumnName == 2001 or x.ColumnName == 2002) ? 0 : 1).ThenBy(x => x.ColumName)
You can use the above code to "pin" certain rows to the top, if you want more granular than that you can use a switch for example to sort specific values into sorted values of 1, 2, 3, 4 and use a higher number for the rest.

You can not change the order or delete a row in a foreach loop, you should create a new datatable and randomly add the rows to new datatable, you should also track the inserted rows not to duplicate

Use a DataView
DataTable result = flokkurDao.GetMCCHABAKflokka("MSCODE");
DateView view = new DateView(result);
view.Sort = "FLOKKUR";
view.Filter = "... you can even apply an in memory filter here ..."
foreach (DataRowView row in view.Rows)
{
....
Every data table comes with a view DefaultView which you can use, this way you can apply the default sorting / filtering in your datalayer.
public DataTable GetMCCHABAKflokka(string tableName, string sort, string filter)
{
var result = GetMCCHABAKflokka(tableName);
result.DefaultView.Sort = sort;
result.DefaultView.Filter = filter;
return result;
}
// use like this
foreach (DataRowView row in result.DefaultView)

DataSet merge + sort not working

I am having trouble sorting a dataset that is merged in the wrong order. Here is the code:
// Adding new data to DataSet ds:
DataSet dsNew = messageSearcher.Seek(_CriteriaCollection.ToString(), mb.ConvertedClassId, mb.ConnectionString); // Recieving a set of ID that are new and need to be added to ds
ds.Merge(dsNew);
// The data set is now sorted wrongly. Therefore want to sort it based on "MME_ID"
var table = ds.Tables[0];
var view = new DataView(table);
var newRows = view.DeepCopy();
newRows.Sort = "MME_ID DESC"; // <--- This does not sort the ResultSet... Why?
table.Rows.Clear();
foreach (var row in newRows)
table.Rows.Add(row);
ds.AcceptChanges();
What am I doing wrong?

A view is just a view, DataView.Sort will not sort the underlying DataTable. I would suggest to use Linq-To-DataSet instead which is more readable and maintainable:
var table = ds.Tables[0].AsEnumerable()
.OrderByDescending(row => row.Field<int>("MME_ID"))
.CopyToDataTable();
Note that i've presumed that MME_ID is an int column. This throws an exception if its a different type like string. Then you eother have to change the Field<T> to use the proper type or - if you want to order numerically instead of lexicographically - parse it to int with int.Parse.

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.

using LINQ to delete specific rows from DataTable

I want to delete a particular row from a DataTable named dt.
For a table in SQL, I could do something like:
DELETE FROM dt
WHERE BASELINE_FOLDER = baselineSubfolder
AND BASELINE_FILE = baselineFilename
AND BASELINE_CHECKSUM = baselineChecksum;
Is there an equivalent LINQ statement for this?

Assuming you don't have the model's and only a DataTable (this is what I understand from the OP).
//Cast to enumerable of `DataRow` and filter on your condition
var rows = dt.Rows.Cast<DataRow>().Where(row => row["BASELINE_FOLDER"] == baselineSubFolder && row["BASELINE_FILE" == baselineFilename
&& row["BASELINE_CHECKSUM"] == baselineChecksum).ToArray();
//Loop through and remove the rows that meet the condition
foreach(DataRow dr in rows)
{
dt.Rows.Remove(dr);
}

you can convert the data table to list and can use RemoveAt() to do so.
You can convert it to list and use the below code
string baseLineFolder=dt.Rows["BASELINE_FOLDER"].ToString();
string baseLineFile=dt.Rows["BASELINE_FILE"].ToString();
string baseLineChecksum=dt.Rows["BASELINE_CHECKSUM"].ToString();
var dtresult = dt.AsEnumerable();
var result=(from r in dtresult
where(r.Field<string>("BASELINE_FOLDER")!=baseLineFolder)
&&(r.Field<string>("BASELINE_FILE")!=baseLineFile)
&&(r.Field<string>("BASELINE_CHECKSUM ")!=baseLineChecksum)
select r).ToList();

How to filter a specific value from a data table

I have five rows in my data table (with column AccountId, Name, Email, Address) and I want to get a specific row on basis of AccountId as all the five rows have different AccountID. I want to filter it on the basis of AccountID. I mean I only need one row from the Data table to process on the basis of AccountId.
How do I get a specfic row from the data table containing the AccountId that I have passed?

Three options:
Use DataTable.Select, providing a filter expression
Iterate over the rows yourself
Use LINQ, with the data table extensions
Personally I'd suggest using the last option (LINQ):
var row = table.AsEnumerable()
.FirstOrDefault(r => r.Field<string>("AccountID") == accountID);
if (row != null)
{
// Use the row
}

Have you looked into the DataTable.Select() method?
http://msdn.microsoft.com/en-us/library/system.data.datatable.select(v=vs.100).aspx
public class DataTableExample
{
public static void Main()
{
//adding up a new datatable
DataTable dtEmployee = new DataTable("Employee");
//adding up 3 columns to datatable
dtEmployee.Columns.Add("ID", typeof(int));
dtEmployee.Columns.Add("Name", typeof(string));
dtEmployee.Columns.Add("Salary", typeof(double));
//adding up rows to the datatable
dtEmployee.Rows.Add(52, "Human1", 21000);
dtEmployee.Rows.Add(63, "Human2", 22000);
dtEmployee.Rows.Add(72, "Human3", 23000);
dtEmployee.Rows.Add(110,"Human4", 24000);
// sorting the datatable basedon salary in descending order
DataRow[] rows= dtEmployee.Select(string.Empty,"Salary desc");
//foreach datatable
foreach (DataRow row in rows)
{
Console.WriteLine(row["ID"].ToString() + ":" + row["Name"].ToString() + ":" + row["Salary"].ToString());
}
Console.ReadLine();
}
}

Example with an array:
http://msdn.microsoft.com/en-us/library/f6dh4x2h(VS.80).aspx
Example with a single Object:
http://msdn.microsoft.com/en-us/library/ydd48eyk
Just use something like this:
DataTable dt = new DataTable();
DataRow dr = dt.Rows.Find(accntID);
Hope this helped you out.