Follow below steps:
- Import M1 & M2 DB in your local system.
- Compare fields of respective product tables from M1 & M2.
- Write query like below(example of sales_shipment table):
INSERT INTO m2_db.sales_shipment (entity_id,store_id,total_weight,total_qty,email_sent,order_id,customer_id,shipping_address_id,billing_address_id,shipment_status,increment_id,created_at,updated_at,packages,shipping_label) (SELECT entity_id,store_id,total_weight,total_qty,email_sent,order_id,customer_id,shipping_address_id,billing_address_id,shipment_status,increment_id,created_at,updated_at,packages,shipping_label FROM m1_db.sni6_sales_flat_shipment);
Note: Please arrange the fields of M1 & M2 in same order.
Hope it'll help.