On Sat, 2009-01-31 at 23:36 +0000, Gregory Stark wrote: > Octavio Alvarez <alvarezp@xxxxxxxxxxxxxxxx> writes: > > > A crosstab is not but a presentational transform of the data set. Any > > information you would eventually need can be taken from the original > > data source, one way or another. That's why dynamic-column crosstab are > > not a problem, and the DBMS should not worry about providing the > > information about the columns, maybe by simply not allowing the > > dynamic-column ones in subqueries. > > What about a WHERE clause like > > WHERE P1 > P2 You could either: (1) do "FROM grades AS g1 INNER JOIN grades AS g2 ON g1.P1 > g2.P2", generating the record set before applying the crosstab transformation. (2) Since you are implying the existence of P1 and P2, use the fixed-number-of-columns crosstab case instead, for which PG would actually be able to give the column definitions without running the query, and after that, joining the results with some other query. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
