[Year 12 IT Apps] IARTV October test

[Mark Kelly]

Oops.  Hit SEND too soon.  The second last para should read:

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 field must 
exist in a limited list.


Mark Kelly wrote:
> 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
McKinnon Rd McKinnon 3204, Victoria, Australia
Direct line / Voicemail: 8520 9085
School Phone +613 8520 9000
School Fax +613 9578 9253
kel at mckinnonsc.vic.edu.au

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