Duplicate handling in SQLAlchemy

I am using SQLAlchemy to write data from Python to a database in SQL. I am using the below code to write the contents of one of the tables in SQL, which would then give me the primary keys for the first table Table 1

, which I use when writing to the data for the next table Table 2

as foreign keys are Table 2

mapped to Table 1

. However, I am now writing a function to prevent duplicate data in these tables if I had to run the script again.

Base.metadata.create_all(engine, checkfirst=True)
Session = sessionmaker(bind=engine)
session = Session(bind=engine, expire_on_commit=False)
# Writing data into Table 1
session.add_all([
Table1(name = 'Euro'),
Table1(name = 'Fed'),
Table1(name = 'Aus'),
Table1(name = 'BOE'),
Table1(name = 'Canada')])

session.flush()
session.commit()
session = Session(bind=engine, expire_on_commit=False)    

#Obtaining the primary keys for Table 1
listofindices = []

for row in session.query(Table 1):
    listofindices.append(row.id)

      

        
        
        
      

    

So far away the code for handling duplicates looks like this. However, I'm not sure how to get the primary keys from Table 1

and at the same time prevent duplicate data in it :

Session = scoped_session(sessionmaker(bind=engine))
s = Session()
select_statement = s.execute('select count(*) from Table 1')
result = select_statement.fetchone()
table_exists = result[0] #Does TABLE 1 exist?
if table_exists != 0:
    #DONT KNOW WHAT TO WRITE HERE TO PREVENT DUPLICATES AS NOW THE TABLE EXISTS