Retrieve external mysql data from inside a post

Hello all,

I am running a blog which has ~10 categories and many posts. It is a shop catalog. You have ~10 categories (which are the locations) and every posts is a different shop. Every post has a table which includes all shop’s data like name,telephone number,address,facilities etc.

What I want to do is to make every post show the data in a table automatically, without needing me every time to copy and paste the data from elsewhere. What I do need is a function that will retrieve a row from the mysql database, and extract the specific cell. Let’s say:

Mc Donalds fast food
Address : Wide Street 123
City: Rome
Location: (a google api map)

The thing is that I am doing this from an html form and a php file not in wordpress. When I move the php file in the wp-includes and run the code from inside the post and exec-php, I receive a bunch of errors.

Can anyone help on this please?