What Is Wrong with SQL Server Client Library DLL, ntwdblib.dll?

The second requirement to access SQL Server with PHP scripts is the SQL Server Client Library DLL, ntwdblib.dll. The good news is that the Windows binary version of PHP 5.2.3 has ntwdblib.dll included in the PHP home directory.

But the bad news is that the included copy of ntwdblib.dll is not compatible with SQL Server 2005. What makes it worse is that no specific error messages is returned from the PHP engine, php_mssql.dll, ntwdblib.dll, or the SQL Server. All you get is "Unable to connect to server: LOCALHOST", and you know that SQL Server is running properly on LOCALHOST.

If you read the PHP manual, it does mention that "copying ntwdblib.dll from \winnt\system32 on the server (SQL Server machine) to \winnt\system32 on the PHP box". This instruction is too short and causes the following confusions:

• Windows binary version of PHP 5.2.3 already has a copy of ntwdblib.dll included. But that copy is not good for SQL Server 2005.
• There is no ntwdblib.dll on the SQL Server 2005 Express Edition machine.
• You don't need to place ntwdblib.dll in \winnt\system32. Placing it in PHP home directory is fine.

⇒ Missing ntwdblib.dll for MSSQL connection

⇐ Turning on the MSSQL API Module

⇑ SQL Server FAQs - PHP MSSQL Functions - Connections and Query Execution

⇑⇑ SQL Server Connection Tutorials