quering layer using result of the query on another layer using php mapscript

[Arunoday Chatterjee]

Basically i'm displaying the county and city data in the first shot and i
want to display streets data as the map is zoomed out. Since the streets
data is huge, it is failing to load hence i need to filter the streets
data. So i was looking for a solution to fetch and display only street
data relevant for the visible region of the map.

Can you pls. let me know how to achieve this?

Also, i have a dropdown of city with the FIP as the value and i want the
map to move to the city location based on user choice. How do i achieve
this?

Do i use filter or expression, as i'm already using an expression
as '[TYPE]' eq 'city' but when i change it to say '[PL_FIP]' eq '00884'
nothing comes up, why is it so?

Just wanted to let you know that i'm generating the map by querying a
dynamic layer with some location content.

Any direction would be very helpful, as there are no advanced php
mapscript example.