I can not add up columns when using a left outer join. Any ideas as to why? - Mailing list pgsql-general

Hi All,

I want to add x and y. John and Joe do not have a “y” value, so the LEFT JOIN returns NULL. Likewise Jane does not have a value for “x” so the LEFT JOIN returns null for her. The “x” and “y” columns are correct, but I would expect the “total” column to have 24, 232, and 4.  myview is a view that converts id numbers to the actual names. run, project and name come from myview. Both x and y come from the site table.

Here is my query:

SELECT project,name,

       site.x,

       site.y,

       (site.x + site.y) AS "total"

FROM myview

LEFT JOIN site ON site.run_id = run

Here is what I get back…

Can anyone tell me why the “total” column is empty?

Does the LEFT JOIN not apply to expressions?

Thanks for any help,

Robert Balzli