PHP Call to Undefined Function: Troubleshooting MSSQL Connection Problems

As you've encountered an error stating "PHP Fatal error: Call to undefined function mssql_connect()", it's essential to understand the underlying cause and resolve it effectively.

The first step is to verify that the Microsoft SQL Server driver has been installed and enabled correctly. Navigate to your php.ini file and check if the following line is present:

extension=php_sqlsrv_53_nts.dll

If this line exists, ensure that the file is loaded in your PHP configuration by confirming the following setting in php.ini:

extension_dir = "ext"

In case the extension_dir path is different, modify it accordingly.

However, you should note that the mssql_connect() function does not belong to the Microsoft SQL Server driver. Instead, you should utilize sqlsrv_connect() to establish a connection with SQL Server from PHP, as suggested in the Microsoft SQL Server driver documentation.

Additional troubleshooting steps include:

• Verify that you're using the appropriate PHP version for the Microsoft SQL Server driver.
• Ensure that the Microsoft SQL Server driver has been extracted to the specified extension directory.
• Examine the SQLSRV_Help.chm file for detailed information on the Microsoft SQL Server driver API.

By following these steps, you should be able to resolve the undefined function error and connect to Microsoft SQL Server 2008 using PHP 5.3 on IIS7/Windows Server 2008.