How do I search for file extension and content in Windows 7?

In the search bar on the upper right hand corner of the file explorer you need to add the prefix type: and content:.

So the search you would perform is "content:table_abc type:.sql" without quotes

Here is an image for reference. In it I searched for a .sql file containing the word "object_data". The search I performed was type:.sql content:object_data

In windows 2012 Search the syntax would be:

file:.sln Project1.proj

or

file:.ext content:"My Content String"

2012 does not recognize type, but does recognize file and content is optional.

This is a good way to find Solutions in a source tree is you know a filename.