To write a php function for a website

We have a website built in an old version of php. It worked fine on the host server, but they were shutting down their server (virtual) that supported this version of php, so I had to move it to another host. Since the move (about 6 months ago) the site goes down regularly. With the host, we've discovered the problem is that within the php code, the user connection with the database is opened but there is no function code to close the connection. Subsequently, the site continually reaches maximum user connections and is 'unable to connect to database'. I need a php developer to write a function that will do the connection, execute the query that you need, then return the query as a array or string, that will be kept into the memory and then close the DB connection. The problem can be intermittent, so I will need it to be checked via the host on the server, so we know it is working.