Links

[Mark Schonewille]

Hi,

I just noticed that the two key1 fields don't have the same name in both 
tables. The field in table1 is called key1, but the field in table2 is 
called xkey1. The contents of the two fields, key1 and xkey1, is identical.

--
Best regards,

Mark Schonewille

Economy-x-Talk Consulting and Software Engineering
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On 8/21/2015 03:39, Mark Schonewille wrote:
> In addition to my previous e-mail, a few more questions.
>
> I have two tables. table1 and table2. Table1 is a very big table and
> table2 is a very small table, considering the number of fields. Both
> tables contain field key1. In table1, key1 is set as the primary key.
> Table2 doesn't have a primary key, but key1 could be set as its primary
> key, although I have another candidate for the primary key.
>
> The two tables are linked as follows:
>
> SET PROPERTY "last_related" OF TABLE "table2" TO 'table1:
> Link_table1_table2 (M:1)';
>
> I now try to insert data into the small table2 with a query like
>
> INSERT INTO table2 (field1, field2, key1, field4)
>    VALUES ('data 1','data 2','0001','data 4')
>
> Table1 already has record with 0001 in field key1, but table2 doesn't
> have such a record. If I run my query, I always get error 0x23502,
> ERR_CONSTRAINT_FOREIGN_KEY_VIOLATION.
>
> What is the explanation for this error?
> Did I set the property incorrectly, e.g. should I use 1:M instead of
> M:1? If so, why?
>
> Since no other database system uses this type of links (according to the
> docs), is it really a good idea to use this type of links? Should I just
> not link table2? What kind of queries does the link make possible, which
> otherwise wouldn't be possible?
>
> --
> Best regards,
>
> Mark Schonewille
>
> Economy-x-Talk Consulting and Software Engineering
> Homepage: http://economy-x-talk.com
> Twitter: http://twitter.com/xtalkprogrammer
> KvK: 50277553
>
> Installer Maker for LiveCode:
> http://qery.us/468
>
> Buy my new book "Programming LiveCode for the Real Beginner"
> http://qery.us/3fi
>
> LiveCode on Facebook:
> https://www.facebook.com/groups/runrev/
>
>
>
> On 8/21/2015 03:19, Mark Schonewille wrote:
>> Hi,
>>
>> I can find in the documentation how to create links, but I can't find
>> the answers to my questions.
>>
>> How exactly do links work?
>> What do 1:M and M:M mean?
>>
>> --
>> Best regards,
>>
>> Mark Schonewille
>>
>> Economy-x-Talk Consulting and Software Engineering
>> Homepage: http://economy-x-talk.com
>> Twitter: http://twitter.com/xtalkprogrammer
>> KvK: 50277553
>>
>> Installer Maker for LiveCode:
>> http://qery.us/468
>>
>> Buy my new book "Programming LiveCode for the Real Beginner"
>> http://qery.us/3fi
>>
>> LiveCode on Facebook:
>> https://www.facebook.com/groups/runrev/
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