Wrong approach. Right list of tables, but wrong approach.
create table WorkerProject (
WorkerId int not null references Workers(WorkerId),
ProjectId int not null references Projects(ProjectId)
);
This is the basic idea. You don't really give the layout of your tables, but the idea is that you add a new row, not a new column. This is called a junction table.
You can add additional information into the table as well. For instance, the date the worker was assigned, who made the assigned, and so on.
I should point out that Oracle is a powerful database that offers other solutions, such as nested tables or JSON encoding. First, though, you should master the basics of how to store relational databases in the SQLish way. If you have specific needs, then there is additional functionality that can help.