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Was the intent of your question to distinguish the pros and cons
of sequential versus random numbers? Sequential numbers never repeat,
and you won't run into trouble until the next number is larger than the
column can hold, which is usually not a problem unless you define the column as
tinyint or something. Random numbers might repeat
since they are only really pseudo-random, but I wouldn't
worry about it, because, again, you're probably
not going to have a table large enough for this to occur.
Random numbers also have the advantage
that you won't be tempted to try SELECT MAX(ID) in order
to get back the key of the latest inserted record -- but
that's a different discussion.
It's more likely that you're interested in the advantages and
disadvantages of a surrogate key as compared to
a natural or "real" primary key.
| Key |
Advantages |
Disadvantages |
|---|
| natural |
|
- bulky
- may repeat
- may be null
- may change
|
|---|
| surrogate |
- lightweight
- unique
- not null
- never changes
|
|
|---|
As you may be able to tell from the above,
the advantages of one are the disadvantages of the other.
This answer is continued.
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