Posted by CountDraculla on 10/02/66 11:43

Fixing Multiple Database bug in adoDB

popular data access layer for php, adoDB can support multiple databases
from different provider at time, but not from same provider. what I
mean is if you instantiate two adoDB connection like this

$db1 = &NewAdoConnection ("mysql");
$db1 = &NewAdoConnection ("oracle");

then you can run queries simultaneously from these connections. but if
you want to access two database from same provider like this

$db1 = &NewAdoConnection ("mysql");
$db1 = &NewAdoConnection ("mysql");
$db1->PConnect(logininfo_for_first_database)
$db2->PConnect(logininfo_for_second_database)

then only last action will remain active and if you use
$db1->execute(), it will actually works on second database. if you want
to access any table from first database, it will generate an error. I
think this is an internal bug in adoDB.

How to fix this bug?

if you open adodb-mysql.inc.php and goto function _connect() you will
find this line at the end

1. if ($argDatabasename) return $this->SelectDB($argDatabasename);

now goto SelectDB function and see what it contains actually.

// returns true or false
function SelectDB($dbName)
{
$this->databaseName = $dbName;
if ($this->_connectionID) {
return @mysql_select_db($dbName,$this->_connectionID);
}
else return false;
}

so it basically returns a boolean value, mysql connection link is
stored in $this->_connectionID variable. Now modify this code like this

1. add this line at the declaration section of adodb-mysql.inc.php

var $__db = array();

2. modify the SelectDB function like this

// returns true or false
function SelectDB($dbName)
{
$this->databaseName = $dbName;
if ($this->_connectionID) {
@mysql_select_db($dbName,$this->_connectionID);
$this->__db[$this->_connectionID] = $dbName;
return $this->_connectionID;
}
else return false;
}

3. Now open the _query function and modify it like this

// returns queryID or false
function _query($sql,$inputarr)
{
//global $ADODB_COUNTRECS;
//if($ADODB_COUNTRECS)
$this->SelectDB($this->__db[$this->_connectionID]);
return mysql_query($sql, $this->_connectionID);
//else return @mysql_unbuffered_query($sql,$this->_connectionID);
// requires PHP >= 4.0.6
}

That's it!!, now your adoDB supports multiple databases from same
provider.

Thanks
Hasin Hayder
http ://groups.yahoo.com/group.phpexperts

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