create table Credito(
    id_credito int primary key identity,
    id_cliente int,
    id_Usuario int,
    concepto varchar(40) not null,
    descripcion varchar(150) not null,
    cantidad_credito float not null,
    fecha_inicio date not null,
    tipo_cuota varchar(10) not null,
    fecha_fin date not null,
    cantidad_cuotas int not null,
    cantidad_mensual float not null,
    estado_credito char(1) not null,
    estado_mora int not null,
    numero_credito int,
    saldo float,
    check (estado_credito='C' or estado_credito='P'),
    check (estado_mora=1 or estado_mora=0),
    check (tipo_cuota='quincenal' or tipo_cuota='mensual'),
    constraint fk_ic foreign key(id_cliente) references Cliente,
    constraint fk_iu foreign key(id_Usuario) references Usuario
);

Public Class Datos
    Dim conex As New SqlConnection
    Dim conectar As String = "Data Source=Desktop-sigtqcfmyserver;Initial Catalog=ProyectoFinal2;Integrated Security=True"
    Public Sub New()
        Try
            conex.ConnectionString = conectar
        Catch ex As SqlException
            MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
        End Try
    End Sub

//Esta es la función que utilizo para actualizar los registros
    Public Sub Actualizar(tabla As String, campos_valores As String, condicion As String)
        Try
            conex.Open()
            Dim cmd As New SqlCommand("update " & tabla & " set " & campos_valores & " where " & condicion, conex)
            cmd.ExecuteNonQuery()
        Catch ex As Exception
            MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
        Finally
            conex.Close()
        End Try
    End Sub
End Class

Public Class Pagos
    Dim obj as New Datos
    Public Sub ActualizarPago()
        If meses >= 1 Then
            cantMora = meses * precioMora **PrecioMora equivale a 2.5**
            tabla = "Credito"
            campos_valores = "Saldo=" & cantMora + saldoPend
            condicion = "numero_credito=" & numero_factura
            obj.Actualizar(tabla, campos_valores, condicion)
        End If
    End Sub
End Class

Dim oldString As String = "32,3"
' Returns "Shipping List".
Dim newString As String = Replace(TestString, ",", ".")