Deleting row from datatable in C

Question

I m having a problem deleting rows from a datatable  In my program  I am reading info from a database into a datatable using an sql query  I use an oledb connection and the code dt Load command ExecuteReader     to do this  Later  I want to delete rows that match an id string  I have tried the following code buy cannot get it to work               DataRow   drr   dt Select  Student       id                        for  int i   0  i  lt  drr Length  i                    dt Rows Remove drr i                dt AcceptChanges      Can anyone please suggest another way with an example

User · Answer

I think the reason the OPs code does not work is because once you call Remove you are changing the Length of drr. When you call Delete you are not actually deleting the row until AcceptChanges is called. This is why if you want to use Remove you need a separate loop.

Depending on the situation or preference...

string colName = "colName";
string comparisonValue = (whatever it is).ToString();
string strFilter = (dtbl.Columns[colName].DataType == typeof(string)) ? "[" + colName + "]='" + comparisonValue + "'" : "[" + colName + "]=" + comparisonValue;
string strSort = "";

DataRow[] drows = dtbl.Select(strFilter, strSort, DataViewRowState.CurrentRows);

Above used for next two examples

foreach(DataRow drow in drows)
{
   drow.Delete();//Mark a row for deletion.
}
dtbl.AcceptChanges();

OR

foreach(DataRow drow in drows)
{
   dtbl.Rows[dtbl.Rows.IndexOf(drow)].Delete();//Mark a row for deletion.
}
dtbl.AcceptChanges();

OR

List<DataRow> listRowsToDelete = new List<DataRow>();

foreach(DataRow drow in dtbl.Rows)
{
   if(condition to delete)
   {
      listRowsToDelete.Add(drow);
   }
}

foreach(DataRow drowToDelete in listRowsToDelete)
{
   dtbl.Rows.Remove(drowToDelete);// Calling Remove is the same as calling Delete and then calling AcceptChanges
}

Note that if you call Delete() then you should call AcceptChanges() but if you call Remove() then AcceptChanges() is not necessary.

Also, here is a good link on row filter syntax.

User · Answer

If you want to remove the entire row from DataTable    try this  DataTable dt   new DataTable       User DataTable DataRow   rows  rows   dt Select  Student       id           foreach  DataRow row in rows       dt Rows Remove row

User · Answer

Advance for loop works better for this case  public void deleteRow DataRow selectedRow                        foreach  DataRow  in StudentTable Rows                                if  SR TableColumn StudentID ToString    ToString      StudentIndex                      SR Delete                               StudentTable AcceptChanges

User · Answer

a simple example   http   www dotnetspark com tutorial 13-42-delete-row-from-datatable aspx  Does this work for you

User · Answer

There several different ways to do it  But You can use the following approach   List lt DataRow gt  RowsToDelete   new List lt DataRow gt      for  int i   0  i  lt  drr Length  i               if condition to delete the row                 RowsToDelete Add drr i                  foreach var dr in RowsToDelete             drr Rows Remove dr

User · Answer

This question will give you good insights on how to delete a record from a DataTable   DataTable  How to conditionally delete rows  It would look like this   DataRow   drr   dt Select  Student       id            foreach  var row in drr     row Delete      Don t forget that if you want to update your database  you are going to need to call the Update command   For more information on that  see this link   http   www codeguru com forum showthread php t 471027

User · Answer

Try using Delete method       DataRow   drr   dt Select  Student       id                for  int i   0  i  lt  drr Length  i            drr i  Delete        dt AcceptChanges

User · Answer

I see a number of answers using the Remove method and others using the Delete method     Remove  according to the docs  will immediately remove the record from the  local  table  and on Update  will not remove a missing record     Delete in comparison changes the RowState to Deleted  and will update the server table on Update   Likewise  calling the AcceptChanges method before the Update to the server table will reset all your RowState s  to Unchanged and nothing will flow to the server    Still nursing my thumb after hitting this a number of times

[c#] Deleting row from datatable in C#

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