Re: Learning Vertical Inheritance
Re: Learning Vertical Inheritance
- Subject: Re: Learning Vertical Inheritance
- From: "Ren, Kevin" <email@hidden>
- Date: Tue, 22 Dec 2009 08:58:04 +1300
- Thread-topic: Re: Learning Vertical Inheritance
Title: Re: Learning Vertical Inheritance
Hi, Dave,
Thanks for your reply,
>Yes. This is the problem with MySQL not being able to initially defer the constraints. If you need to use MySQL, I suggest that you remove the Foreign Key constraint between STUDENT and PERSON in the database and trust that EOF will keep everything correct for you.
In my case PERSON is abstract class not TABLE in DB, do you mean remove the Foreign Key constraint between Address and Home_address?
No problem with that sequence, problem is try insert STUDENT first instead of ADDRESS.
If it's MYSQL issue, why it's working sometimes with correct generated SQL, like address, home_addres then student.
If EOF, WOnder or somebody else have some code to check this order of the insert table name has the right sequence, that would be working.
>I would also suggest that you avoid using Vertical Inheritance if you can. It is very inefficient when creating select statements in the database. It does make the database more normalized, but at the cost of efficiency. In this situation I would use Single Table Inheritance instead.
I am just try to verify VI is working in EOF. Yes maybe need change to horizontal inheritance or Single Table Inheritance instead.
thanks
Xiaowen(Kevin) Ren
Analyst Programmer
Channel Applications, Retail Applications
ANZ National Bank Ltd
Level 6 ASB Tower
2 Hunter Street
PO Box 1791
Wellington
Phone: 04 4365363
Fax: 04 8028696
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