This is a really complicated issue. Here are the details of (in)compatibilities so someone else might spend less time searching and trying.
PHP extension sqlsrv from Microsoft
sqlsrv exists in two (+ an unofficial) versions, they are only compatible with 32-bit PHP. There is currently no version for 64-bit PHP.
- sqlsrv version 2.0 is compatible with PHP 5.2.4 to 5.3.x and SQL Native client 2008 R2 to connect to Microsoft SQL Server 2000, 2005, or 2008.
- sqlsrv version 3.0 is compatible with PHP 5.3.0 to 5.4.x and SQL Native client 2012 to connect to Microsoft SQL Server 2005, 2008, 2008 R2, and SQL Server 2012.
- no official version currently supports PHP 5.5
- There is an unofficial version of SQLSRV 3.0 on Rob's Area that does not require SQL Native client 2012 but should run with previous SQL Native clients. I didn't yet try this one.
ODBC extension of PHP
An other way to access SQL Server 2000 with PHP 5.4 is through the odbc extension. It is possible to connect using three ODBC drivers for SQL Server 2000:
- SQL Server ODBC client version 6.00 that comes preinstalled with Windows 2008 R2
- SQL Server Native Client 9.0 (SQL Server 2005 feature pack)
- SQL Server Native Client 10.0 (SQL Server 2008 R2 feature pack)
The code for the connection for each of those ODBC Drivers:
$connection_string = 'DRIVER={SQL Server};SERVER=mbsql;DATABASE=vg1';
$connection_string = 'DRIVER={SQL Native Client};SERVER=mbsql;DATABASE=vg1';
$connection_string = 'DRIVER={SQL Server Native Client 10.0};SERVER=mbsql;DATABASE=vg1';
$connection = odbc_connect( $connection_string, $user, $pass );
These connections work with PHP 32 bit and 64 bit. I din't yet test which one is the best.