Repeated MySQL queries from Python return the same data

You need to commit the connection after each query. This commits the current transaction and ensures that the next (implicit) transaction will pick up changes made while the previous transaction was active.

# Main loop
while True:

    # SQL query
    sql = "SELECT * FROM table"

    # Read the database, store as a dictionary
    mycursor = mydb.cursor(dictionary=True)
    mycursor.execute(sql)

    # Store data in rows
    myresult = mycursor.fetchall()

    # Transfer data into list
    for row in myresult:
        myList[int(row["rowID"])] = (row["a"], row["b"], row["c"])

        print(myList[int(row["rowID"])])

    # Commit !
    mydb.commit()
    print("---")
    sleep (0.1)

The concept here is isolation levels. From the docs (emphasis mine):

REPEATABLE READ

This is the default isolation level for InnoDB. Consistent reads within the same transaction read the snapshot established by the first read.