import sqlite3

sqlite_file = 'my_first_db.sqlite'
table_name = 'my_table_2'
id_column = 'my_1st_column'
new_column1 = 'my_2nd_column'
new_column2 = 'my_3nd_column'
column_type = 'TEXT' # E.g., INTEGER, TEXT, NULL, REAL, BLOB
default_val = 'Hello World'


conn = sqlite3.connect(sqlite_file)
c = conn.cursor()

c.execute("ALTER TABLE {tn} ADD COLUMN '{cn}' {ct}"\
        .format(tn=table_name, cn=new_column1, ct=column_type))

c.execute("ALTER TABLE {tn} ADD COLUMN '{cn}' {ct} DEFAULT '{df}'"\
        .format(tn=table_name, cn=new_column2, ct=column_type, df=default_val))

conn.commit()
conn.close()

