How to display search results from different categories with PHP and MySql -

i working on classifieds website, , have question retrieving search results.

my goal display number of classifieds in each category next category-names.

for instance:

what ideal way of getting these counts mysql database tables?

is write 1 query every single table in database? mean lot of queries 1 visitor, , perhaps cause performance issues?

thanks

update:

i haven't created mysql table yet, feel free recommend ideal structure if plays big role in counting.

i prefer have 1 query need.

assuming have categories table , no of classifieds products should able this:

    select c.category, count(p.id) productscount  categories c left join products p on c.id = p.category_id group c.category     order c.category

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