What is the best way to build mysql+php+html interaction?

Question

MySQL

Essence of the question: I'm trying to transfer values ​​from the mysql database to the html file (bootstrap3),
html does not accept the php script (htaccess made changes still does not work), I
tried to rename it to php - the bootstrap3 components (dropdown menu, carousel, etc.) stop working. ) Please tell me what could be the error or the working version of the interaction - the simplest example is better so that you can get either a value or a table from the mysql database,
thanks in advance

Answer 1

In htaccess:
AddType application/x-httpd-php .html