Hi :)
So in the editing can you change the direction? or rather the way that
the relationships works?
Regards from
Tom :)
------------------------------------------------------------------------
*From:* Girvin R. Herr <girvin.herr@sbcglobal.net>
*To:* Tom Davies <tomdavies04@yahoo.co.uk>
*Cc:* Dan Lewis <elderdanlewis@gmail.com>;
"users@global.libreoffice.org" <users@global.libreoffice.org>
*Sent:* Thursday, 10 January 2013, 21:44
*Subject:* Re: [libreoffice-users] Re: Base scenario
Tom,
Yes. I confirmed that right-clicking on a join line does allow
deleting or editing.
If I understand you correctly, no, relationship definitions should
not be part of the back-end. The table relationship is defined
for the back-end by the front-end through the SQL statements. For
example, I have a table of suppliers, with names and addresses and
other contact information. This table is related to almost all of
my database (main) tables. Additionally, each "main" table has
its own set of table relationships with other (sub?) tables, most
of which are for selecting options with a join. Each record of
these option tables contains a primary key and a text field for
the option. For example, I have a table of statuses for the item
in the main table record. An integer foreign key in the main
table contains a primary key value corresponding to the text
element of the statuses table record. That way, I am only storing
an integer (key value) in the main table, rather than the option
text, and with no repeated option text. It also standardizes the
option texts. All of these multiple relationships must be defined
by me - ergo it needs to be in the front-end.
Hope this helps clarify this.
Girvin Herr
Tom Davies wrote:
> 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
<mailto:elderdanlewis@gmail.com>>
>> To: users@global.libreoffice.org
<mailto: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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