while filling data grid view using sql reader application getting slow - vb.net

Question

I have a windows form...i am trying to fill my data grid view using sql datareader,,
while clicking button i try to fill my data grid view..
i wrote one function for filling grid view..
Sub filldgv()
DGVReleased.Rows.Clear()
Dim carid As String
Dim VehicleNo As String
Dim DriverID As String
Dim krrt As Integer
Dim Dt As Integer
Dim cmd As New SqlCommand("IBS_fetchresleaseVehicle", con.connect)
cmd.CommandType = CommandType.StoredProcedure
cmd.Parameters.Add("#locid", SqlDbType.Int).Value = Glocid
dr = cmd.ExecuteReader
While dr.Read
If dr("TBarcode") Is DBNull.Value Then
carid = ""
Else
carid = dr("TBarcode")
End If
If dr("PlateNo") Is DBNull.Value Then
VehicleNo = ""
Else
VehicleNo = dr("PlateNo")
End If
If dr("DelEcode") Is DBNull.Value Then
DriverID = ""
Else
DriverID = dr("DelEcode")
End If
If dr("KRRT") Is DBNull.Value Then
Else
krrt = dr("KRRT")
End If
If dr("DT") Is DBNull.Value Then
Else
Dt = dr("DT")
End If
Dim row0 As String() = {carid, VehicleNo, DriverID, krrt, Dt}
DGVReleased.Rows.Insert(0, row0)
End While
dr.Close()
con.disconnect()
End Sub
then i am calling this function in my button click event.here first am removing all records from grid view then i am filling..while coming more records to data grid view my system is getting hang..is there any way to do this very simple manner..any help is very appreciable..

Answer 1

use DataGridView.Rows.AddRange. Collect data in List(Of DataGridViewRow), then only after the loop add them to the DataGridView:
Sub filldgv()
Dim ListRows As New List(Of DataGridViewRow)()
Dim cmd = New SqlCommand("IBS_fetchresleaseVehicle")
cmd.CommandType = CommandType.StoredProcedure
cmd.Connection = con.connect
cmd.Parameters.Add("#locid", SqlDbType.Int).Value = Glocid
Dim dr = cmd.ExecuteReader
Dim ListRows As New List(Of DataGridViewRow)()
While dr.Read
Dim DgvRow = New DataGridViewRow
Dim o = {dr("TBarcode").ToString(),
dr("PlateNo").ToString(),
dr("DelEcode").ToString(),
If(IsDBNull(dr("KRRT")), 0, dr("KRRT")),
If(IsDBNull(dr("DT")), 0, dr("DT")) }
DgvRow.CreateCells(o)
ListRows.Add(DgvRow)
End While
dr.Close()
con.disconnect()
Dim SavedBool = DGVReleased.AllowUserToAddRows
DGVReleased.AllowUserToAddRows = False
DGVReleased.Rows.AddRange(ListRows.ToArray())
DGVReleased.AllowUserToAddRows = SavedBool
End Sub
Use DataTable & DataBinding, then populate DataTable in Background-Thread:
Sub filldgv()
Dim dt As New DataTable
dt.Columns.Add("", GetType(String))
dt.Columns.Add("", GetType(String))
dt.Columns.Add("", GetType(String))
dt.Columns.Add("", GetType(Integer))
dt.Columns.Add("", GetType(Integer))
DGVReleased.DataSource = dt
Task.Factory.StartNew(Sub() Populate(dt))
''you can replace last line with this:
'Dim bgw = New BackgroundWorker()
'AddHandler bgw.DoWork, Sub() Populate(dt)
'bgw.RunWorkerAsync()
End Sub
Sub Populate(dt As DataTable)
Dim cmd = New SqlCommand("IBS_fetchresleaseVehicle")
cmd.CommandType = CommandType.StoredProcedure
cmd.Connection = con.connect
cmd.Parameters.Add("#locid", SqlDbType.Int).Value = Glocid
Dim dr = cmd.ExecuteReader
While dr.Read
Dim o = {dr("TBarcode").ToString(),
dr("PlateNo").ToString(),
dr("DelEcode").ToString(),
If(IsDBNull(dr("KRRT")), 0, dr("KRRT")),
If(IsDBNull(dr("DT")), 0, dr("DT")) }
dt.Rows.Add(o)
End While
dr.Close()
con.disconnect()
End Sub
Tip:
instead the if conditions, you can use shortly If Operator:
So instead:
If IsDBNull(dr("TBarcode") Then
carid = 0
Else
carid = dr("TBarcode")
End If
Written:
carid = If(IsDBNull(dr("TBarcode")), 0, dr("TBarcode"))
Thanks to #SSS: For String Fields you can simply:
carid = dr("TBarcode").ToString()