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2008/03/28 18:15
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pradeep
Joined: 2008/03/28
Messages: 1
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I am having difficulty in undersand the difference between one-to-many association between two classes aggregation relationship betweeen two classes. Are they same? Can they overlap?
thanks
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2008/03/31 13:33
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LilianWong
Joined: 2008/02/22
Messages: 278
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Hi pradeep,
Thanks for your post. In fact, they are not the same.
One-to-many association does not specify the characteristics of the relationship while aggregation does.
Aggregation is the part-of relationship. It's like saying that a car has an engine and wheels as its part.
I hope this explanation can help. If you have any further inquiries, please feel free to ask.
Best regards,
Lilian Wong
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2008/03/31 14:54
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Hi Wong,
If I have understood you well, then it means that if a PERSON has one-to many relationship with ADDRESS then, a PERSON's characteristic is not defined or identified by ADDRESS. So A PERSON is not an aggregation of ADDRESS while a PERSON has one-to-many relationship with ADDRESS.
Thanks for the explanation. 
-pradeep
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2008/04/01 15:38
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LilianWong
Joined: 2008/02/22
Messages: 278
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Hi pradeep,
Actually, aggregation specifies the characteristics of the relationship between two classes, but it is not necessary to be one-to-many relationship.
Will it be more clear? If there are any inquiries, please feel free to ask.
Best regards,
Lilian Wong
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2008/04/14 04:37
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Guruli
Joined: 2007/08/15
Messages: 7
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Hi pradeep,
The easiest way to remember aggregation ist, that it shows "has-a " relationship. It can be one-one, one-many or any other relationships.
Assiziation just defines, that classes have relationship.
I hope it will help.
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2008/05/16 17:06
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2008/05/16 17:07
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2008/05/16 17:16
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