On 15 Jan 2003 at 16:31, Marko Asplund wrote: > > i'm trying to port an existing application from Oracle8i to PostgreSQL but > i'm having problems understanding a certain outer join query type used in > the application. the query includes a normal outer join between two tables > but also uses outer join syntax to join a table with a constant. here's a > simplified version of the query: > > SELECT doc.id,doc.title,sub.user_id,sub.operation > FROM document doc, document_subscription sub > WHERE 6 = sub.user_id(+) AND sub.document_id(+) = doc.id; > > what does the '6 = sub.user_id(+)' condition exactly do in this query? > how would this be translated SQL92 join syntax used by PostgreSQL? > > i've tried converting it to: > > SELECT doc.id,doc.title,sub.user_id,sub.operation > FROM document doc LEFT OUTER JOIN document_subscription sub > ON sub.document_id = doc.id > WHERE (sub.user_id = 6 OR sub.user_id IS NULL); > > but this query is missing the rows in the documents table which have a > corresponding document_subscription row with 'not user_id = 6'.
What about this: SELECT doc.id,doc.title,sub.user_id,sub.operation FROM document doc LEFT OUTER JOIN document_subscription sub ON sub.document_id = doc.id; id | title | user_id | operation ----+-------+---------+----------- 1 | doc1 | 5 | op1 2 | doc2 | 5 | op2 2 | doc2 | 6 | op2 4 | doc4 | | (4 rows) > > here're also simplified definitions of the two tables used in the query > and some test data: Thanks for supplying the table and data. That makes things much easier. -- Dan Langille : http://www.langille.org/ ---------------------------(end of broadcast)--------------------------- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/users-lounge/docs/faq.html
