When using the Windows Search functionality, you can search for words inside files. By default this doesn't seem to work for .sql or .php files however.

To enable this, add the following key to the registry:

HKEY_CLASSES_ROOT\.sql\PersistentHandler\(Default) : {5e941d80-bf96-11cd-b579-08002b30bfeb}

This will associate the plain text filter (System32\Query.dll) to the specific file type, making it possible to search the content of the file. The reason not all extensions have this enabled by default, is due to performance considerations from Microsoft's point of view. I personally haven't noticed any visible performance problems from enabling it for SQL and PHP files.

Log off and log on again. From then on you can use the search box to search inside SQL and PHP files. A quick way to make Windows recognize the change, is by killing the explorer.exe process and starting a new one. That way you don't have to close any programs.

At pilif.ch you can find a nice tool to set the PersistentHandler to the plain text filter.

Give it a try and search for 'SELECT'.