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Can some one explain me what are multi valued attributes and what are compoist attributes? what is the difference?
Please help me....
2 Replies - 796 Views - Last Post: 14 January 2012 - 07:56 AM
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sandaruwanc
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What are Multi valued Attributes and Composit Attributes [Er Diagrams]
Posted 12 January 2012 - 07:06 AM
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William_Wilson
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Re: What are Multi valued Attributes and Composit Attributes [Er Diagrams]
Posted 13 January 2012 - 05:54 PM
A composite attribute is a multi-value attribute by definition, but not the other way around.
If you consider a phone number as a composite attribute the set of values has a pattern and order which determines it's meaning as a whole value.
Ex: (country code)-(area code)-(local directory)-(home id)
While I can put together words or numbers in a combination which gives a multiple valued entry, but not in a meaningful way.
Say animals a person likes, ex:
hippo, dog
dog, cat, bird
cat, bird
bird, cat
These are all multi-valued attributes, but the last 2 are the same without being identical. where as someone with the phone-number 111-222-1234 is not the same as someone with the phone number 222-111-1234 despite the individual values being the same.
Basically they are both lists, but order and value type is far more important in a composite attribute.
If you consider a phone number as a composite attribute the set of values has a pattern and order which determines it's meaning as a whole value.
Ex: (country code)-(area code)-(local directory)-(home id)
While I can put together words or numbers in a combination which gives a multiple valued entry, but not in a meaningful way.
Say animals a person likes, ex:
hippo, dog
dog, cat, bird
cat, bird
bird, cat
These are all multi-valued attributes, but the last 2 are the same without being identical. where as someone with the phone-number 111-222-1234 is not the same as someone with the phone number 222-111-1234 despite the individual values being the same.
Basically they are both lists, but order and value type is far more important in a composite attribute.
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sandaruwanc
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Re: What are Multi valued Attributes and Composit Attributes [Er Diagrams]
Posted 14 January 2012 - 07:56 AM
William_Wilson, on 14 January 2012 - 06:24 AM, said:
A composite attribute is a multi-value attribute by definition, but not the other way around.
If you consider a phone number as a composite attribute the set of values has a pattern and order which determines it's meaning as a whole value.
Ex: (country code)-(area code)-(local directory)-(home id)
While I can put together words or numbers in a combination which gives a multiple valued entry, but not in a meaningful way.
Say animals a person likes, ex:
hippo, dog
dog, cat, bird
cat, bird
bird, cat
These are all multi-valued attributes, but the last 2 are the same without being identical. where as someone with the phone-number 111-222-1234 is not the same as someone with the phone number 222-111-1234 despite the individual values being the same.
Basically they are both lists, but order and value type is far more important in a composite attribute.
If you consider a phone number as a composite attribute the set of values has a pattern and order which determines it's meaning as a whole value.
Ex: (country code)-(area code)-(local directory)-(home id)
While I can put together words or numbers in a combination which gives a multiple valued entry, but not in a meaningful way.
Say animals a person likes, ex:
hippo, dog
dog, cat, bird
cat, bird
bird, cat
These are all multi-valued attributes, but the last 2 are the same without being identical. where as someone with the phone-number 111-222-1234 is not the same as someone with the phone number 222-111-1234 despite the individual values being the same.
Basically they are both lists, but order and value type is far more important in a composite attribute.
Thankx .... But, can u explain me further ? I feel like , I didn't get u correctly...
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