Re: select * from dual in MOUNTED database returns 4 columns (one row)

I can't remember when it came in, but when the database is not open, select * from dual is implemented by

    select * from x$dual;

It's been around for AGES, and I can't think why all the stuff in standard.sql (such as the pl/sql USER, or UID calls) doesn't use it instead of incurring the logical I/O of using the proper DUAL table.

--
Jonathan Lewis
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Richard Foote wrote in message ...


>Hi Vsevolod,

>

>I must admit I've never tried to select from dual before with an unopened

>database so I'm not sure what you are actually accessing (I suspect some

>internal dual like object). What I do know is that you are not accessing

the


>dual table/synonym as this is only accessible with an open database so I

>would strongly suspect they are not one and the same.

>

>Regards

>

>Richard

>"Vsevolod Afanassiev" <vafanassiev_at_aapt.com.au> wrote in message

>news:4f7d504c.0207082214.506816ea_at_posting.google.com...

>> If a database is mounted (not opened), then

>>

>> select * from dual

>>

>> returns 4 columns (one row).

>> However, when the database is opened,

>>

>> select * from dual

>>

>> returns one column only.

>>

>> I checked DBA_OBJECTS - there are only two objects with name DUAL,

>> both in SYS schema, table and synonym.

>>

>> Thanks,

>> Sev

>

>