I have three tables. traffic, sales and dates. Both the traffic table and the sales table has multiple entries per date with each row representing the date, some subdivision, and the total. For example every day five divisions could be reporting their sales so there would be five entries in the sales table for that date. The dates table just has one field and it just has a date in it (unique). I set that up for testing purposes. I have the following query which I am trying to make sense of. select (select count(id) from sales) as sales_count, (select count(id) from traffic) as traffic_count, (select count(traffic.date) from traffic inner join sales on traffic.date = sales.date) as two_table_join_count, (select count(dates.date) from dates inner join traffic on dates.date = traffic.date inner join sales on sales.date = dates.date) as three_table_join_count; running this query gives me this result 169157; 49833 ;25121853; 25121853 On the third select (two table join) it doesn't matter if I change it to a right join, full join left outer join I get the same number so it looks like it's doing a cross join no matter what. It also doesn't matter if I do a select count(*) Could somebody explain what is happening here? Thanks. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
