[postgis-users] Need an answer for somebody new to GIS and PostGIS

[Brian Harbick]

I have a data set of 1 million rows of addresses that have lat/long.  
I do not know the source of the geocoding.

I need to be able to query the database for addresses within 10 miles  
of a point.

I have compared my attempts with results with results from Google API.

On one address, google said it was 8 miles away. PostGIS results said  
4 miles. Since, I live in the area that I tested 8 miles is most  
likely the correct answer.

I have tried using SRID -1 and 4326 and both do not match with google.

I admit I have been hacking at this for two weeks and read hundreds  
of posts in the forum, but have not found an answers that I can rely on.

I think that PostGIS is meant for point in polygon type queries,  
which I will need next. but, right now I am just trying to make sure  
I understand how to setup the geometry correctly to test for miles.

Please help point in the right direction with as much detail as  
possible.

Thank You.