What is unique_id in Oracle and what's the use of it

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newa - 30 Jan 2008 03:47 GMT

Hi,

I am new to Oracle and today someone asked me about the "fference
between unique_id and primary key. Which to use and why?" I know about
the primary key but not unique_id. Can someone kindly give me an
overview of it?

Thanks in advance.

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news.verizon.net - 30 Jan 2008 06:04 GMT

> Hi,
>
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>
> Thanks in advance.

What does it sound like?
Jim

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Robert Klemme - 30 Jan 2008 07:19 GMT

>> Hi,
>>
[quoted text clipped - 6 lines]
>
> What does it sound like?

Homework question.

:-)

robert

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venki - 30 Jan 2008 11:01 GMT

> Hi,
>
[quoted text clipped - 4 lines]
>
> Thanks in advance.

Primary key is the combination of NOTNULL constraint and unique key
constraint.
so it ll never allow duplicate and null value.But unique key allows
number of null value but it never allow duplicate value.
Do not compare this to MS sqlserver, bcoz it some what different from
oracle to sql. Bcoz unique key will alow only one null value.

venki

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Mark D Powell - 30 Jan 2008 14:36 GMT

> > Hi,
>
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>
> venki

This question or minor variations of it have been asked many times.
Here is a brief explanation of what PK, UK, and FK constraints are and
the indexes used to support them.

What is the difference between a unique index and a unique constraint?
http://www.jlcomp.demon.co.uk/faq/uk_idx_con.html

HTH -- Mark D Powell --

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