Arrays in SQL feel needlessly complicated. The traditional way is to have a one-to-many relationship, aka create a whole new table for each array you create.

So for a social media app, you can't store a user's posts in your users table. You have to make a new table:

create table posts(
    postId int auto_increment primary key,
    authorId int,
    postContent varchar
);

This makes sense here, but what if we wanted each post to have multiple authors? We can't just do:

create table posts(
    postId int auto_increment primary key,
    authorId int array,
    postContent varchar
);

Instead, we would need a weird table like this:

create table post_authors(
    postAuthorId int auto_increment primary key,
    postId int,
    postAuthor int
);

This is the SQL way to handle arrays. But I don't like it. So sometimes I'll use JSON.stringify() and store my arrays as strings. This makes searching a lot harder though.