the many worldly proceed formulating comma-separated strings collection/array/list?

during work databases i beheld i query strings strings i have put several restrictions where-clause list/array/collection. should feeling this:

select * fan 
where customer.id (34, 26, ..., 2);

you foster shortening doubt have collection strings wish emanate comma-separated list strings only string.

my proceed i have used distant something that:

string outcome = "";
boolean initial = true;
for(string twine : collectionofstrings) {
    if(first) {
        result+=string;
        first=false;
    } else {
        result+=","+string;
    }
}

but unequivocally ugly. can't happens there initial look, generally assembled strings (like each sql query) removing complicated.

what your (more) glorious way?