Seb wrote:
---<---------------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.
The way I usually handle this is as follows.
SELECT foo - bar AS baz FROM (
SELECT a.a + b.a AS foo, a.b + b.b AS bar FROM a JOIN b ON a.id = b.id
) AS subtable;
Although, I'm not really sure that's The Right Way to do it.
Colin
