Re: Need help with OUTER JOIN

On 18 November 2011 17:44, Matt Foster <Matthew(dot)Foster(at)noaa(dot)gov> wrote:
> I'm having trouble getting the desired results from an OUTER JOIN, and I'm
> hoping I can get some help here.
>
> My first table, office_list, has a column, office, that is a static list of
> all field office identifiers in our area.  The second table,
> verification_data, contains data that is submitted daily by the field
> offices.  The verification_data table contains columns for the office ID
> (also office), a timestamp (start_time), and other various data.  I'm
> needing to perform a query that will always give me a complete list of
> offices (i.e. everything from the first table), plus a field from the second
> table, and is also conditional on the timestamp and a few other tests.
>
> Here is what I have been trying, unsuccessfully...
>
> SELECT office_list.office, verification_data.period
> FROM office_list
> LEFT OUTER JOIN verification_data USING (office)
> WHERE start_time > 'yesterday'
> AND start_time < 'today'
> AND period=1
> AND name='foo'
> AND element='bar';
>
> The result is that I only get rows where there are matches between the two
> tables.
>
> Where have I gone awry?

Well are there any records in verification_data which don't have an
"office" column value which is listed in the office_list table? If
not, all records will match. I'm not sure what you're expecting to
get back.

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Thom Brown
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