Hello ,

        The id will be automatically created , you dont have to give an id to the record.

        Other than Using Query , You Can Try

        sale_order_line_id = self.env['sale.order.line'].create({
            'order_id':order_id,
            'product_id':product_id,
            'product_uom_qty':quantity,
            'price_unit':unit_price
})

    in this manner give every detailes of the order line and you can create an order line by code

    the line will appear on the order which's id is given as the order_id

Hi Sushma,

This is how inserts in query

query = """ INSERT INTO {rel} ({id1}, {id2})

                        (SELECT a, b FROM unnest(%s) AS a, unnest(%s) AS b)

                        EXCEPT (SELECT {id1}, {id2} FROM {rel} WHERE {id1} IN %s)

                    """.format(**parts)

Regards,

Hello, 

Check below link i think it's help you 

https://stackoverflow.com/questions/34362637/sql-many2many-query

Yes we can insert using query.

many2many have a relational table. so insert into the relational table, it will work