Change background color of TextBox inside GridView when Blank in ASP.Net

You will need to find all TextBoxes and check whether empty and then change color. I have done for one TextBox

Protected Sub GridView1_RowDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs) Handles GridView1.RowDataBound
    If e.Row.RowType = DataControlRowType.DataRow Then
        If e.Row.DataItem("bloodgp") Is System.DBNull.Value <> True AndAlso e.Row.DataItem("bloodgp") Then
            e.Row.BackColor = Drawing.Color.LightGreen
            'Change color of TextBox
            Dim TextBox1 As TextBox = TryCast(e.Row.FindControl("TextBox1"), TextBox)
            If TextBox1.Text.Trim() = "" Then
                TextBox1.BackColor = Drawing.Color.Azure
            End If
        End If
    End If
End Sub