referencing column aliases in select list

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От Seb
Тема referencing column aliases in select list
Дата
Msg-id 874paiz2r1.fsf@patagonia.sebmags.homelinux.org
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Ответы Re: referencing column aliases in select list
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Hi,

I have a SELECT statement that is a bit involved in terms of
calculations, so I wanted to set up some column aliases and refer to
them further down the select list:

---<---------------cut here---------------start-------------->---
SELECT table1.col1 - table2.col1 AS diff1,
    table1.col2 + table2.col2 AS sum1,
    sum1 - diff1
FROM table1 INNER JOIN table2 ON (table1.id = table2.id)
---<---------------cut here---------------end---------------->---

but this fails with the error message that sum1 column is not known.
How can one get around this?  The calculations are quite involved and
would be difficult and error-prone to repeat them anywhere they're
needed in the select list.  Thanks in advance for any pointers.


Cheers,

--
Seb

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