In my last post I described a “Select Distinct“ function for a datatable. This is a whole lot easier using Whidbey. You can get a distinct table based on a column in the DefaultView of the datatable:
DataTable d = dataSetName.dataTableName.DefaultView.ToTable(true, new string[] { "ColumnName" });
I needed to perform a “Select Distinct“ on a datatable, not in the database, for binding to a listbox. Found a good solution here. Modified it according to one of the comments to use a hash table so sort order won't matter. Here is my version of the function:
private DataTable SelectDistinct(DataTable sourceTable, string sourceColumn)
{
DataTable result = null;
try
{
result = new DataTable();
result.Columns.Add(sourceColumn, sourceTable.Columns[sourceColumn].DataType);
Hashtable ht = new Hashtable();
foreach (DataRow dr in sourceTable.Rows)
{
if (!ht.ContainsKey(dr[sourceColumn]))
{
ht.Add(dr[sourceColumn], null);
DataRow newRow = result.NewRow();
newRow[sourceColumn] = dr[sourceColumn];
result.Rows.Add(newRow);
}
}
return result;
}
catch (System.Exception ex)
{
ExceptionManager.Publish(ex);
return null;
}
finally
{
if (result != null)
result.Dispose();
}
}