Primary Key Index

[skydesigns]

I guess this will sound like a very silly question, but here goes:

If I understand correctly, a Primary Key is an "index". So, is there ever any reason to add another index to the primary key field? Exprimenting with mySQL I found that it was possible to do it, but does it serve any purpose?

Thank you for your help!

Matt

 

[cDevX99]

If the index is precisely the same as the key, it serves no purpose at all. If, however, you were to index on the key in combination with another field(s) upon which you frequently search your table then it is certainly a good idea.

Jim

 

[NixerX]

Primary Key is for Refernecing a specific record

Index keys are for outright query speed!
I have never seen:

select * from table name where INDEXED_TABLE='data';

as opposed to

select * from table name where PRIMARY_KEY='data';


NixerX