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Peter, et al --
...and then Peter Brawley said...
%
% Your reference to "having the table sorted" suggests physical table sorting,
Right...
% but a basic characteristic of a relational DBMS is that data retrieval does
% not depend on physical row order. The actual order of rows in a MySql table
OK. That's what I figured, especially since I didn't see anything about
how to insert a record sorted or unsorted or such, but couldn't find
anything authoritative.
% is entirely arbitrary, and shouldn't be your concern except perhaps for huge
% OLAP tables.
Right. That's why, when they're needed, database architects are *really*
needed :-)
%
% So I think the question you are asking comes down to this: when does an
% index provide a performance advantage? One answer is: when the rows you are
That's the second question, figuring that indexed fields are what is
going to make things faster :-)
% retrieving form a very small subset of the table you are querying, the
% effect of the index then vbeing to greatly diminish the number of rows that
% have to be physically read to return the desired result set.
That sounds like this case... A hundred or a thousand clients, and I
want the card or cards for just one of them. And so... How does this
look?
Assuming a table 'clients' with a client ID and a table 'cards' with a
card ID (since multiple related clients might use the same card, or more
particularly since I will probably separate the actual card numbers
behind a security scheme), is
create table ccards
(
# ID number
id int not null default 0 auto_increment primary key ,
client int , # references client.id
index (client) , # fast indexed lookups
type varchar(10) , # MC, Visa, AmEx, Disc, ... maybe a set()?
card int # references cards.id
) ;
a valid definition? And, meanwhile, how about
create table clients
(
# ID number
id int not null default 0 auto_increment primary key ,
# last, first names
lname varchar(40) ,
index (lname) ,
fname varchar(40) ,
index (fname) ,
mname varchar(40) ,
...
) ;
for a client table with indexed first and last name fields?
%
% PB
I'll ask about char vs varchar and text next time :-)
Thanks & HAND
mysql query,
:-D
- --
David T-G * There is too much animal courage in
(play) [EMAIL PROTECTED] * society and not sufficient moral courage.
(work) [EMAIL PROTECTED] -- Mary Baker Eddy, "Science and Health"
http://www.justpickone.org/davidtg/ Shpx gur Pbzzhavpngvbaf Qrprapl Npg!
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