Duplicate Validation in code(vb)

How can I check for a record that exists before insert in code behind.

eg

In the below I want to check that the @QUALSCHEMEID exist or not

 Public Sub InsertGCH()

            'If Session("ModeType") = "Insert" Then

            Dim strConnString As String = ConfigurationManager.ConnectionStrings("IrisConnectionString").ConnectionString

            Dim con As New SqlConnection(strConnString)

            Dim cmd As New SqlCommand()

            cmd.CommandType = CommandType.StoredProcedure

            cmd.CommandText = "Insert_REVIEWS_GCH"

            'cmd.Parameters.Add("@TRAINEEID", SqlDbType.NVarChar).Value = Request("TRAINEEID")

            'cmd.Parameters.Add("@POT", SqlDbType.Int).Value = Request("POT")

            cmd.Parameters.Add("@QUALSCHEMEID", SqlDbType.Int).Value = ddlQUALSCHEMEID.SelectedValue.Trim()

            cmd.Parameters.Add("@ReviewID", SqlDbType.Int).Value = Session("REVIEWS")

            cmd.Parameters.Add("@GCH", SqlDbType.NVarChar).Value = txtGCH.Text.Trim()


            cmd.Connection = con



            con.Open()

            cmd.ExecuteNonQuery()




            con.Close()

            con.Dispose()





        End Sub

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