Regarding Join

[adeeb alexander]

Hi,
I actually have three rows in addissue table but when i run this query i am getting nine. Here expiry is a view.

   
select a.added,a.curr_date,e.days from addissue a,expiry e;

So please any body correct me.
Thanks and regards.

[Campbell Ritchie]

Not sure, but you are not joining anything. I think it would work better with a WHERE clause, otherwise you get the Cartesian Product of the lines in the table and the lines (presumably also 3; 3*3=9) in the view.

[V.M. Kaufmann]

Adeeb,

If you have:

select a.added,a.curr_date,e.days from addissue a,expiry e;

you need to relate the tables. For example if the relationship is that you want the expiry days for the given added issue, there should be a column that identifies which issue it is in AddIssue, and then a column that joins with it in Expiry.

e.g. select a.added, a.curr_date, e.days from addissue a, expiry e
where a.id = e.addissue

Here is more information on joins: http://www.w3schools.com/Sql/sql_join.asp

[Campbell Ritchie]

That is exactly the sort of thing I meant, V. M. Koffman, and we hope to make you feel welcome here at JavaRanch