[Year 12 IT Apps] IARTV October test

[Mark Kelly]

Thanks, Robert.  So the RI option is turned off by default when creating 
a relationship?

Timmer-Arends wrote:
> Hello Mark
> 
> Access does not automatically enforce referential integrity. Its an 
> option presented to you when you create a relationship, and you can 
> totally ignore it. If you do you can delete records in the 'one-table' 
> quite happily without the 'many-table' being at all affected.
> 
> Regards
> Robert T-A
> Brighton SC
> 
> ----- Original Message ----- From: "Mark Kelly" <kel at mckinnonsc.vic.edu.au>
> To: "Year 12 IT Applications Teachers' Mailing List" 
> <itapps at edulists.com.au>
> Sent: Thursday, September 03, 2009 2:23 PM
> Subject: [Year 12 IT Apps] IARTV October test
> 
> 
>> Hi all.
>>
>> Anyone else using the CSE's IARTV October test for ITA?
>>
>> I'm having issues with one of its database questions (4c):
>>
>> "A one-to-many relationship is established between the Employees Table 
>> and the Locations table.
>>
>> Explain why setting this relationship would prevent a row in the 
>> location table being deleted if some employees were still allocated to 
>> that location."
>>
>> The suggested answer is "Setting a relationship will prevent deletion 
>> of any row that is used as a key in an existing relationship - 
>> referential integrity."
>>
>> This is just not true, at least in Filemaker.  You certainly can 
>> delete a record in a related table when local records still reference 
>> it. Do other databases behave differently?
>>
>> Secondly, as I understand it, referential integrity (at least in 
>> Filemaker) is not automatically created when a relationship is set up. 
>> It's a deliberate strategy to ensure that values can only selected 
>> from an existing list of options.
>>
>> e.g. a person can only be allocated to a location that exists in the 
>> location table.  This can be done by forcing employees' locations be 
>> selected from a drop-down list whose contents are populated 
>> automatically with values from the locations list.  You can also set 
>> up a validation rule stating that the value in the location
>>
>> Again, do other databases have referential integrity enforced by the 
>> RDBMS - and how do they do it?
>>
>> -- 
>> Mark Kelly
>> Manager - Information Systems
>> McKinnon Secondary College
>> kel AT mckinnonsc.vic.edu.au
>> McKinnon Rd, McKinnon 3204, Victoria, Australia
>> Direct line / Voicemail: 8520 9085 Fax +613 9578 9253
>>
>> Webmaster - http://www.mckinnonsc.vic.edu.au
>> IT Lecture notes: http://vceit.com
>> Moderator: IT Applications Mailing List
>>
>> Why do people mis-spell 'grammar' and mispronounce 'pronuniciation'?
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> 
> _______________________________________________
> http://www.edulists.com.au - FAQ, resources, subscribe, unsubscribe
> IT Applications Mailing List kindly supported by
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> Teachers Association Inc
> 
> 

-- 
Mark Kelly
Manager - Information Systems
McKinnon Secondary College
kel AT mckinnonsc.vic.edu.au
McKinnon Rd, McKinnon 3204, Victoria, Australia
Direct line / Voicemail: 8520 9085 Fax +613 9578 9253

Webmaster - http://www.mckinnonsc.vic.edu.au
IT Lecture notes: http://vceit.com
Moderator: IT Applications Mailing List

Why do people mis-spell 'grammar' and mispronounce 'pronuniciation'?