Cracked it! The buffer command
(setAttribute(PDO::MYSQL_ATTR_USE_BUFFERED_QUERY, TRUE)) needs to be
sent to the PDO object, not PDO::Statement objects. The documentation is
wrong here, in a number of ways.
This is the function that (fingers crossed) runs a SELECT query and
returns the statement, while setting the variable passed as the second
parameter to the number of rows. If no second paramater is passed, of
course nothing is set and function avoids unnecessary DB calls.
found_rows() returns the total number of turns regardless of any LIMIT
clause in the SQL so if you use LIMIT, pass the same number as the last
parameter. Offset doesn't matter.
Example Call (notice chopped SQL, no "SELECT"):
$c = -1;
$s = DM::select( '* FROM foo WHERE bar < 40 LIMIT 4 OFFSET 2', $c, 4);
var_dump($s->fetchAll()); # Normal dump of found data
var_dump($c); # The number of rows found, at most 4.
Function:
public static function select($sql, &$count = NULL, $limit = NULL)
{
$db = self::handle(); # Get PDO
$sql = 'SELECT '.(!is_null($count)?'SQL_CALC_FOUND_ROWS ':'').$sql;
try {
$stmt = $db->prepare($sql);
$stmt->execute();
if (!is_null($count)) {
$rows = $db->prepare('SELECT found_rows() AS rows');
$rows->execute();
$rows_array = $rows->fetch(PDO::FETCH_NUM);
$rows->closeCursor();
$count = $rows_array[0];
if (!is_null($limit) && $count > $limit) {
$count = $limit;
}
}
} catch (PDOException $e) {
# todo
}
return $stmt;
}
Rob
Rob C wrote:
So would it be possible to write a select() function to handle the
wierdness? I'm attempting to write one but I'm getting buffered query
errors. This function is part of a Database Manager class and is
supposed to return a PDO::Statement with the number of rows being stored
in a referenced paramater.
Error:
'SQLSTATE[HY000]: General error: 2014 Cannot execute queries while other
unbuffered queries are active. Consider using PDOStatement::fetchAll().
Alternatively, if your code is only ever going to run against mysql, you
may enable query buffering by setting the
PDO::MYSQL_ATTR_USE_BUFFERED_QUERY attribute.' in
E:\Server\swi\qpf\mng\data.class.php:64 Stack trace: #0
E:\Server\swi\qpf\mng\data.class.php(64): PDOStatement->execute() #1
E:\Server\swi\www\db.php(13): DM::select('* FROM cdrs WHE...', 20, -1)
#2 {main} thrown in E:\Server\swi\qpf\mng\data.class.php on line 64
Function:
public static function select($sql, &$count = NULL, $limit = NULL)
{
$db = self::handle(); #Singleton method to create/retrieve db handle
$buf = array(PDO::MYSQL_ATTR_USE_BUFFERED_QUERY => TRUE);
$sql = 'SELECT '.(!is_null($count)?'SQL_CALC_FOUND_ROWS ':'').$sql;
$stmt = $db->prepare($sql, $buf);
$stmt->execute();
if (!is_null($count)) {
$rows = $db->prepare('SELECT found_rows() AS rows', $buf);
$rows->execute(); #ERROR HERE
$rows_array = $rows->fetch(PDO::FETCH_NUM);
$rows->closeCursor();
$count = $rows_array[0];
if (!is_null($limit) && $count > $limit) {
$count = $limt;
}
}
return $stmt;
}
Where am I going wrong here?
Rob
Micah Stevens wrote:
There's a function called 'found_rows()' function, so you could try
issuing a query, then issuing a second one 'SELECT FOUND_ROWS();' and
it should give the number of rows returned by the previous select.
Here's details:
http://dev.mysql.com/doc/refman/4.1/en/information-functions.html
On Tuesday 08 November 2005 9:13 am, Micah Stevens wrote:
yeah, it would help if I read the whole post. Sorry.
On Tuesday 08 November 2005 9:06 am, Dwight Altman wrote:
I suppose you could use "count( PDOStatement::fetchAll() )", but I
understand your amazement.
mysql_num_rows() is specific to MySQL. He wants a PDO version.
-----Original Message-----
From: Micah Stevens [mailto:micah@xxxxxxxxxxxxxxxxxx]
Sent: Tuesday, November 08, 2005 10:51 AM
To: php-db@xxxxxxxxxxxxx
Subject: Re: [PDO] Number of rows found by Select
mysql_num_rows()
On Tuesday 08 November 2005 5:17 am, Rob C wrote:
What is the recommended way to find the number of rows found by a
SELECT query? PDOStatement::rowCount() doesn't work with MySQL and
is a
bit of a hack anyway. Doing a COUNT(*) before the SELECT is very
hackish - the data could have changed and it's an extra query. What is
there that's better than either of these? Is there any way to use
COUNT(*) without risking data change, such as inside a transaction?
I'm amazed that there is no mysql_num_rows() equivilent, I get the
feeling that I'm missing something obvious. I can only presume
there is
some technical limitation that I'm not appreciating, if anyone can
shed
some light on this, I'd like to know.
I'm new to both PDO and this mailing list, so please be gentle with
me.
I'm using PDO 1.0RC2, PHP 5.0.5 and MySQL 4.1.15.
Rob
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