How do I let user choose the conditions in mysql query through nodejs ?

See more:

MySQL

Node.js

I have a program which show reports of students i habe multipile dropdown lists in my page and what the supervisor do is selecting what he wants to show first " for example students who live in usa " /ps i have multi dropdown lists /then my program show him all records in database of these filters .. but my query is not working what i do is

"Select * from students as s where" +"(" + address.length ==0+"||" +address.includes('s.adr') "

Notes ; Address.length ==0 because i want to all the records in case of the supervisor did not choose country and and wanted all countries in th DB ,,,,

Also note that addres is array containig all the countries that supervisor choose

What i am doing wrong here and how can i correct it or how i can do this in other ways

Thanksss

What I have tried:

"Select * from students as s where" +"(" + address.length ==0+"||" +address.includes('s.adr') "