On Wed, 04 Jul 2001, Mohan Khurana wrote:
> database enthusiasts,
>
> I'm fairly new to database administration and development, I'm currently
> still learning about features of databases so that I can ensure that my
> design for the database that I create will be correct. I will be storing
> general pieces of information in an index table that will store an ID #,
> which I wish to be incremented as more people are added to the index, the
> ID # should start with 0. The index will also contain information like
> their name, the date of the last visit to the construction site, and how
> many total days they have worked. One thing I'm not clear about is the
> notion of a "primary key". Is this provided just to allow for faster
> SQL calls that access records using that primary key? Does specifying a
> primary key provide for more functionality in any way?
A primary key is a piece of information that uniquely identifies that piece of
data. It can be a number, a string, or even a group of numbers and/or strings,
but is has to exist (it cannot be null or lacking a value). It is basically
the building block of all relational databases.
I would suggest getting a good book on database theory that will explain the
basics of keys, normalization, and E-R diagrams. My favorite is "Database
Systems: Design, Implementation, and Management" by Peter Rob and Carlos
Coronel.
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--
John Meyer
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Programmer
Those who sacrifice liberty for security deserve neither -- Ben Franklin
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