How to change row color in datagridview by comparing two columns from different tables using vb.net? - vb.net

Question

No success!
If user of tblcon with billmonth of tbltrns exists in tbltrns then highlight the rows of tblcon with red color
Code:
Private Sub checkexist()
For Each row As DataGridViewRow In DataGridView1.Rows
ConObj = New SqlConnection(ConStr)
ConObj.Open()
Dim qry As String = "SELECT * FROM tblTrns WHERE userName=#userName and bill_month=#bill_month"
CmdObj = New SqlCommand(qry, ConObj)
CmdObj.Parameters.AddWithValue("#bill_month", DateTimePicker1.Text)
CmdObj.Parameters.AddWithValue("#userName", (row.Cells("User").Value.ToString))
drObj = CmdObj.ExecuteReader()
If drObj.HasRows Then
row.DefaultCellStyle.BackColor = Color.Red
End If
Next
ConObj.Close()
End Sub
Query for the Grid
Public Function GetData() As DataView
ConObj = New SqlConnection(ConStr)
ConObj.Open()
CmdObj = New SqlCommand
dsObj = New DataSet
daObj = New SqlDataAdapter()
Dim SelectQry = "SELECT UserName[User],doj[Connection Date],packagename[Package],profilename[Profile],billing[Payment],fees[Fees],connectionstatus[Status] from TblCon"
CmdObj.CommandText = SelectQry
CmdObj.Connection = ConObj
daObj.SelectCommand = CmdObj
daObj.Fill(dsObj)
TvObj = dsObj.Tables(0).DefaultView
Return TvObj
ConObj.Close()
End Function
Query Changed in getdata but no success. Please guide ...........................................................................................................................................................................................................................................
Public Function GetData() As DataView
ConObj = New SqlConnection(ConStr)
ConObj.Open()
CmdObj = New SqlCommand
dsObj = New DataSet
daObj = New SqlDataAdapter()
Dim SelectQry = Dim SelectQry = "SELECT UserName[User],doj[Connection Date],packagename[Package],profilename[Profile],billing[Payment],fees[Fees],conn‌​‌​‌​ectionstatus[Status], (SELECT ISNULL(COUNT(*), 0) FROM tblTrns WHERE tblTrns.userName = tblCon.UserName AND bill_month = '" & DateTimePicker1.Text & "') [Comparison] from TblCon"
CmdObj.CommandText = SelectQry
CmdObj.Connection = ConObj
daObj.SelectCommand = CmdObj
daObj.Fill(dsObj)
TvObj = dsObj.Tables(0).DefaultView
Return TvObj
ConObj.Close()
End Function

Answer 1

I recommend you to fill a new column in your grid with a value for comparison and set it's visibility to false.
You can do that by a subselect or a left join on the second table (if you wish an example just post the query that fills your grid).
Based on your comparison column you can use the CellPainting event of the GridView. Like this:
Private Sub grdGridView_CellPainting(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellPaintingEventArgs) Handles grdGridView.CellPainting
If e.RowIndex >= 0 Then
If grdGridView.Rows(e.RowIndex).Cells("colComparison").Value <> "0" And Not IsNothing(grdGridView.Rows(e.RowIndex).Cells("colComparison").Value) Then
e.CellStyle.BackColor = Color.OrangeRed
e.CellStyle.SelectionBackColor = Color.IndianRed
End If
End If
End Sub