How to get many data at once?

In response to "窦德厚(ddh)" <doudehou@gmail.com>:

Hi, if I have such a table:

t_ref_id t_data
--------------------
1 'abc'
2 '321'
1 'ddd'
2 'xyz'
9 '777'
...

I want to get data with a special t_ref_id:

SELECT t_data FROM THETABLE WHERE t_ref_id = '1';

I must use a while loop to extract the data (I'm using PHP):

$rows = array();
while (($row = pgsql_fetch_assoc($result) !== false) {
$rows[] = $row;
}

And if there are many matched rows, such as many hundreds or thousands of
rows, I think such a loop maybe inefficient.

You're wrong. It's pretty much the only way.

The only way you can improve on that is to process that row immediately
instead of copying it from $row to $rows[].

How to do this in a more efficient way?

Use a more efficient language, such as C, instead of PHP.

--
Bill Moran
Collaborative Fusion Inc.
http://people.collaborativefusion.com/~wmoran/

wmoran@collaborativefusion.com
Phone: 412-422-3463x4023

Hi,

PHP has several functions related to postgresql - including a function to
fetch all the rows of the resultset at once into an array and then have a
loop that extracts one row at a time from that :

http://in.php.net/manual/en/function.pg-fetch-all.php

search for all functions with pg_ prefix --- they are PHP functions
relating to PostgreSQL. You need not fetch rows one by one from pg, instead
fetch all the result rows into a php array and then loop to read them one by
one from that array.

Regards,
Chandra ASGI

On Thu, Aug 7, 2008 at 7:03 AM, 窦德厚(ddh) <doudehou@gmail.com> wrote:

Try to use

SELECT ARRAY(SELECT t_data FROM THETABLE WHERE t_ref_id = '1') AS v;

In PHP you may fetch all matched values as a single string and then - use
explode() to split it into values (possibly with later stripslashes).
It is much faster than fetching a thousands of rows.

On Thu, Aug 7, 2008 at 3:03 PM, 窦德厚(ddh) <doudehou@gmail.com> wrote: