Re: [libreoffice-users] base - join same table multiple times

On Mon, 2012-01-23 at 13:14 -0500, Calvin Kim wrote:
> On 01/23/2012 08:26 AM, Werner F. Bruhin wrote:
> > I have the following:
> >
> > tablea
> > - id
> > - name
> >
> >
> > tableb
> > - id
> > - type
> > - total
> > - tablea_id
> >
> > In tableb there can be multiple records for a record in tablea.
> >
> > Like to get to this:
> >
> > tablea.id, tablea.name, tableb1.total1 (if type = 1), tableb2.total2 
> > (if type = 2)
> >
> > I tried to setup a view where I link tableb twice to tablea, but I 
> > can't figure out how to define things with regards to the relation.
> >
> > In SQL it would be something along these lines:
> >
> > SELECT DISTINCT `table1`.`name`, `tableb1`.`total`, `tableb2`.`total` 
> > FROM `tablea`
> > LEFT OUTER JOIN `tableb` as `tableb1` ON `tablea`.`id` = 
> > `tableb1`.`tablea_id` AND `tableb1`.`type` = 1
> > LEFT OUTER JOIN `tableb` as `tableb2` ON `tablea`.`id` = 
> > `tableb2`.`tablea_id` AND `tableb2`.`type` = 1
> >
> > Is this possible with base in LibrOffice 3.3.2, but could upgrade if a 
> > newer version provides this functionality.
> >
> > Thanks in advance for any tips.
> > Werner
>
> I'm no guru, and I just thought about it in my head. So it will 
> definitely not work...
>
> SELECT
>      tablea.id,
>      tablea.name,
>      (SELECT total FROM tableb WHERE type = 1 LIMIT 1) AS `Type1 Total`,
>      (SELECT total FROM tableb WHERE type = 2 LIMIT 1) AS `Type2 Total`
> FROM
>      tablea, tableb
> WHERE
>      tablea.id = tableb.tablea_id;
>
>
> cK

     My thinking is that you do not have enough fields in tableb. What
you should have is
 tableb
- id
- type
- total
- tablea1_id     foreign key
- tablea2_id     foreign key

     You will have two relationships:
tablea.id = tableb.tablea1_id where type = 1
tablea.id = tableb.tablea2_id where type = 2

     A form for this would have tablea as the main form and tableb as
the sub form. Records in the sub form will fall into one of two
categories for a given value of the field Name: type =1 or type =2 but
not both.
     I'm also thinking that a query using both tables could be used. I'm
not sure how you would want to sort the query. You might want to sort
first by the field type (ascending) and second by the field Name
(ascending). This would first give you all the data for when type =1.
Within this sort, you would have an alphabetical sorting for values of
the Name field.

--Dan


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