Обсуждение: How to get many data at once?
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.
How to do this in a more efficient way?
Thank you!
--
ddh
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.
How to do this in a more efficient way?
Thank you!
--
ddh
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 :
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:
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.
How to do this in a more efficient way?
Thank you!
--
ddh
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.
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:
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.
How to do this in a more efficient way?
Thank you!
--
ddh