Re: Request for clarification

Hi Kona Andres,

> Question 1 -
> I am inferring from the above that in *any* ADQL query, it
> is necessary to declare an alias for each and every table referenced
> in that query - is that correct? In other words, the unambiguous
> query "select ra,dec from mytable" is invalid ADQL because it lacks
> an alias declaration for mytable?

Yes, you must have table alias in ADQL.
"select ra, dec from mytable" should be "select ra, dec from maytable t".

> Question 2 -
> As I understand it, SQL uses the syntax "from table as t" rather than
> "from table t" when declaring aliases. Am I incorrect here, or if
> not, should we be including the "as" keyword in our ADQL/s alias
> declarations?

You may omit "as" keyword. So both "from table t" and "from table as t" are valid.

> Question 3 -
> If it is compulsory to declare aliases for all tables, is it also
> compulsory to *use* table alias prefixes for all column references
> in a query, even when they are otherwise unambiguous?

No. You don't need to use the table alias prefix if it is unambiguous.

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Yuji SHIRASAKI, Research Fellow             +81-422-34-3579 (tel)
National Astronomical Observatory of Japan  +81-422-34-3840 (fax)
Osawa, Mitaka, Tokyo, Japan                 yuji.shirasaki-at-nao.ac.jp