Re: [libreoffice-users] Re: Base scenario

Hi :)
Can you right-click on a relationship's join-line and edit it's properties?  Shouldn't the 
relationships be part of the back-end rather than defined in the front-end?  
Regards from
Tom :)  





> ________________________________
> From: Dan Lewis <elderdanlewis@gmail.com>
> To: users@global.libreoffice.org 
> Sent: Wednesday, 9 January 2013, 4:14
> Subject: Re: [libreoffice-users] Re: Base scenario
>
> Comment inline below.
>
> --Dan
>
> On 01/08/2013 07:07 PM, Girvin R. Herr wrote:
> > Ian,
> > Have you actually drawn any relationships?  Base will not do that for you.  Just adding the 
> > tables in the 'Relationships Window' will not create the relationships automagically.  You must 
> > click and hold on the one table element (remote key) and drag over to the related table's 
> > element (primary key), then release the mouse button.  Base will then draw a line between the 
> > two.  Note, the order of the drag is important.  It determines the type of join. Joins are 
> > confusing to me too, so I can't help much there.  I had to experiment with the direction to get 
> > it to work right.  I think it was remote key to primary key, but I am not sure of that any more.
> >
> > Warning!  The way the SQL language is set up, if either of the ends of a join (relationship) is 
> > NULL, then the record will be discarded and not show up in your result set.  No warnings, no 
> > errors.  Data records will just be missing.  IMHO, this is stupid (my mantra is: "thou shall not 
> > lose data"), but that is how the SQL language was set up.  So, make sure any joined data 
> > elements in all of your table records are not NULL.  Note that NULL is not zero (0) and 
> > vice-versa!  NULL means that there is no data in the record element.  I use a lot of remote keys 
> > in my database main tables that point to primary keys (options) in other tables.  In those other 
> > tables, I have made it a point to make the data elements of the first record to be "-", which is 
> > my equivalent of unknown, just to have something to select that is not NULL.  You could probably 
> > use a blank (" "), but I prefer seeing the "-" in forms and reports.  Most times in reports, it 
> > is hard
 to see anyway.  Seeing the "-" tells me the field is not NULL.
> > Hope this helps.
> > Girvin Herr
>       These statements about joins do not seem to be quite correct. What you are describing is an 
> Inner Join: you will only see the rows of data in which both the foreign (remote) key and the 
> primary key have a value.
>      Suppose we have two tables A and B and that the foreign (remote) key is in table A and the 
> primary key is in table B.
>     Example 1: table A Left Outer Join table B. The output (result set) for this contains all the 
> fields in table A and their values on the left side of the combined table. The right side contains 
> all the fields in Table B. The rows in which the primary key value matches the foreign key value, 
> data from both table appear in the output. However, where there is no primary key value in table B 
> that matches the foreign key value in table A, all the fields from table B for that row will be 
> NULL.
>      Example 2: table A Right Outer Join table B. The output for this contains all the fields in 
> table B and their values on the right side. For each output row in which the foreign key does not 
> have a value that matches any value of the primary key, the fields in the left side of it will be 
> NULL.
>      Example 3: table A Cross Join table B. This is also referred to as a Cartesian Product. In 
> this case, each row of table A is joined to all the rows of table B. This contains all of the 
> possible combinations of combining both tables. Usually, some rows of the output will have the 
> table A fields all showing NULL while others will have the fields of table B showing all NULL.
>
> > Ian Whitfield wrote:
> > > Hi All
> > >
> > > Re - My previous post.... Have been doing some Googling etc and found the 'Relationships 
> > > Window' for setting Relationships.
> > >
> > > I can get the Window up, select my Tables but it _DOES NOT_ draw any connecting lines or set 
> > > any Relationships!!??
> > >
> > > Is this another "Gotcha" of using MySQL and Base together? As it does _NOT_ seem to work at 
> > > all!!
> > >
> > > I'm using PCLinuxOS 2012, LO Base 3.6.2.2 and MySQL 5.1.55
> > >
> > > IanW
> > > Pretoria RSA.
>
>
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