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Message Posted: Tue, 04 May 2004 @ 19:16:05 GMT


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Subj:		Re: Dummy objectname in FROM clause

From:		Dieter Noeth

Anomy Anom wrote:

Isn't there a dummy objectname you can specify in Teradata SQL where you must include the FROM clause even though you don't actually need to access a table?

There's no DUAL ;-)

I know in some cases you don't need the FROM clause, e.g., 'SELECT DATE;'. But for example queries with UNION will fail:

     select 1
     union
     select 0;

     3888:  A SELECT for a UNION,INTERSECT or MINUS must reference a table.

Using Derived Tables:

     select * from (select 1 as x) dt
     union
     select * from (select 0 as x) dt;

Look at that stupid explain.

I could swear I heard about this 'dummy table' in a Teradata Education class a few years ago but have never had occasion to use it.

It wasn't me ;-)

I know there are alternatives to this logic, but I am seeking an answer to this specific question.

     create table dummy(x int not null primary key check (x = 1));

     ins into dummy(1);

     select 1 from dummy where x = 1
     union all
     select 0 from dummy where x = 1;

Dieter


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