Asp.Net Filter Datatable by Column

Filter Datatable by Rows

If you need to get subset of a big dataset into datatable Rowwise …

Dim dtEmp as DataTable
Dim dsEmployee as New DataSet

dsEmployee = someobject.getdata()  'dataset can be populated in many ways which is not explained here.

Dim sExpr as String
Dim drRows() as DataRow, drSingleRow as DataRow

sExpr = "EmpID > 100"  'Condition

drRows = dsEmployee.Tables(0).Select(sExpr)

'If you need to add Sort Order it can be added to sExpr

Dim sSortOrder as String
sSortOrder = "EmpName DESC"
drRows = dsEmployee.Tables(0).Select(sExpr,sSortOrder)

For Each drSingleRow in drRows
 dtEmp.ImportRow(drRows)
Next

' Datatable dtEmp has filtered records

Filter Datatable by Column

If you need to get subset of big dataset into datatable columnwise…

Dim dtEmp as DataTable
Dim dsEmployee as New DataSet

dsEmployoee = someobject.getdata()  'dataset can be populated in many ways which is not explained here.

'This copies the structure and data

dtEmp = dsEmployee.Tables(0).Copy

dtEmp.Columns.Remove("Unwanted Column 1")
dtEmp.Columns.Remove("Unwanted Column 2")
dtEmp.Columns.Remove("Unwanted Column 3")

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Copy Datatable from one Dataset to another Dataset

 Copying a datatable from one dataset  to another was not that straightforward as I thought.

Dim dsSource As New DataSet
Dim dsDestination As New DataSet

'Your way to get data from XML or DB.
dsSource = object.getdata()

dsDestination = object.getmoredata()

'This is important, without this it will result in error
'when you try to copy the datatable from one dataset to another

dsSource.Tables(0).TableName = "NewTableName"

dsDestination.Tables.Add(dsSource.Tables(0).Copy)

dsDestination.Tables(0).Tablename = "SomeTable"
dsDestination.Tables(1).Tablename = "NewTableName"   'The one we copied from other Dataset

Note 1 : When you are using more than one datatable in a dataset it is advisable you name the datatables.

Note 2 : These kinds of scenarios arise, when you are trying to establish Relation between datatables in a dataset.

(Cascading master – detail relation)