Visual Basic

Dim cmdText As String = "SELECT * from tblStaffInfo tbl WHERE tbl.CampusName = '" & strCampusName & "'"

Private Function GetDataSource(strCampusName) As DataTable
    Dim conxnString As String = "Data Source=Raabi\SQLEXPRESS;Initial Catalog=StaffReport; Integrated Security=True"
    Dim cmdText As String = "SELECT * from tblStaffInfo tbl WHERE tbl.CampusName = @CampusName"
    
    Using conxn As New SqlConnection(conxnString)
        Using cmd As New SqlCommand(cmdText, conxn)
            cmd.Parameters.AddWithValue("@CampusName", strCampusName)
            
            Dim DGVadapter As New SqlDataAdapter(cmd)
            Dim ds As New DataSet()
            DGVadapter.Fill(ds)
            Return ds.Tables(0)
        End Using
    End Using
End Function

Mycroft Holmes wrote:

Declaring a const within a method is just wrong, it should be a class level constant!

Mycroft Holmes wrote:

Having declared it you do not use it instead you use My.Settings.MySqlConnectionString which does not exist.

Using da = New MySqlDataAdapter(sqlSelect, con)

Using con = New SqlConnection(My.Settings.SqlServerConnectionString)
    Using da = New SqlDataAdapter(sqlSelect, con)
        da.Fill(table)
        Return table
    End Using
End Using

Dim conxnString As String = My.MySettings.sqlConnectionString

Dim conxnString As String = My.Settings.sqlConnectionString

Private Function cboCampuses_SelectedValueChanged(sender As Object, e As EventArgs) Handles cboCampuses.SelectedValueChanged
       Dim selectedValue As String
       selectedValue = cboCampuses.SelectedValue
       Me.StaffEvaluationDGV.DataSource = GetDataSource(selectedValue)
   End Function

   Private Function GetDataSource(selectedValue) As DataTable
       Dim sqlSelect As String = "SELECT * FROM tblEvaln " &
          "WHERE CampusName = " & selectedValue

       Dim SqlConnection As SqlConnection
       Dim conxnString As String = My.MySettings.sqlConnectionString
       Try
           Dim table = New DataTable()
           Using con = New System.Data.SqlClient.SqlConnection(conxnString)
               con.Open()
               Using da = New System.Data.SqlClient.SqlDataAdapter(sqlSelect, con)
                   da.Fill(table)
                   Return table
               End Using
           End Using
       Catch ex As Exception
           ' Error message here
       End Try
   End Function