Using Apache PHP to access MS SQL mssql ( installation )

1. Microsoft SQL Server
Connection Troubles
ntwdblib.dll - The most common issue is that you do not have the ntwdblib.dll file installed in your PHP extension directory. This library can be found with your Enterprise Manager dll's or in your SQL servers system32 folder. It's generally best to take the file from the server where SQL Server is installed.Related forum post: Unable to connect to the database PHP.net: Information on the PHP MSSQL extension, lots of good tips in the user comments
ntwdblib.dll Version - On some systems the ntwdblib.dll version is too old to work correctly with PHP. If your version does not end in 80.194.0 it's probably too old. You can download the 80.194 version here.
SQL Client Tools - On some servers you will need to install the SQL Server client tools. This is especially true if your SQL Server is on a different server than your web server.
(local) Registration - If your SQL Servers registered name is (local) you'll need to delete that registration and change the registration to the machine name. You should then be able to set the cDBHOSTNAME in config.php to 'localhost' and be able to connect.
SQL Authentication - The SQL Server must be setup to use both SQL Server authentication and windows authentication. Both for the user as well as the server as a whole. This setting is in SERVER_NAME->Properties->Security
privileges - The HelpSpot database user must have sufficient privileges to access the database. Making them the database owner will work, though other configurations may also be effective. The database user will also usually need to have public access enabled.
port number - On some PHP/SQL Server installations you'll need to provide the port number your SQL Server listens for requests on. You can do this by adding a comma and the port number to the cDBHOSTNAME variable like this: "db.mycompany.com,1433"
TCP/IP in SQL Server 2005 - In order to connect by IP you may need to specifically allow that protocol by going to the SQL Server Configuration Manager, go to protocals and then enabled TCP/IP.
Registry key - In rare cases an edit to the registry may help.[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSSQLServer\Client\ConnectTo]"DSQUERY"="DBNETLIB"