Question

Well, I didn’t know how to explain this one on the title, so I’ll be clearer here.

I have a couple of tables:

TiposDeCatalogo:

PK IdTipoCatalogo (int) 
IdVendedor (int)
Nombre (string)
Descripcion (string)
Estado (string)
FechaAlta (date)

Catalogo: 

PK IdCatalogo (int) 
IdTipoCatalogo (int)
IdVendedor (int)
Nombre (string)
Descripcion (string)
Estado (string)
FechaAlta (date)

There is a foreign key on Catalogo.IdTipoCatalogo = TiposDeCatalogos.IdTipoCatalogo

I need a query that can show all rows on TiposDeCatalogo that have already been registered on Catalogo

For instance…

TiposDeCatalogos has the following rows

IdTipoCatalogo IdVendedor Nombre Estado FechaAlta

1   1   Catalogos de Ventas     Activo  20/08/2012
2   1   Catalogos de CRM        Activo  20/08/2012
3   1   Catalogos de Inventario     Activo  20/08/2012
4   1   Catalogos de Facturacion        Activo  04/09/2012
5   1   Catalogos de Cobranza       Activo  04/09/2012
6   1   Catalogos de Admin      Activo  04/09/2012
7   1   Catalogos de Admin      Activo  04/09/2012
8   1   Catalogos de Finanzas       Activo  04/09/2012
9   1   Catalogos de Clientes       Activo  04/09/2012
12  1   Catalogos de Administ General       Activo  04/09/2012

Then Catalogo has the following rows

IdCatalogo IdTipoCatalogo IdVendedor Nombre Estado FechaAlta

1   1   17  Formas de Pago  formas de pago para las ventas  Activo  01/09/2012
2   5   1   Tipos de Moneda     Activo  05/09/2012
3   2   1    Tipos de Agendamiento      Activo  05/09/2012
4   3   1   Tipos de Precios        Activo  06/09/2012
5   5   1    TIpos de Moneda        Activo  06/09/2012
6   3   1   Tipo de Presentacion        Activo  06/09/2012

You might notice that in Catalogo, only the following IdTipoCatalogo have been registered (1, 2, 3, 5)

So what I want, is a query that shows me those TiposDeCatalogos (only once each, so the query should only return 4 rows in this example)….

I hope you can help me, thanks

Answer 1

You can use EXISTS to accomplish this:

SELECT
    tc.IdTipoCatalogo,
    tc.IdVendedor,
    tc.Nombre,
    tc.Estado,
    tc.FechaAlta
FROM TiposDeCatalogos tc
WHERE EXISTS (
    SELECT 1
    FROM Catalogo c 
    WHERE c.IdTipoCatalogo = tc.IdTipoCatalogo 
)

Alternately, you could use a JOIN and DISTINCT:

SELECT DISTINCT
    tc.IdTipoCatalogo,
    tc.IdVendedor,
    tc.Nombre,
    tc.Estado,
    tc.FechaAlta
FROM 
    TiposDeCatalogos tc
    JOIN Catalogo c ON c.IdTipoCatalogo = tc.IdTipoCatalogo 

However, this will likely be less efficient, because the DISTINCT will require the additional operation to exclude the duplicates produced by the JOIN.