Tables

There are three tables Sheets, SheetSongs and Songs;

Sheets and Songs are Many-to-Many Relationships

Table SheetSongs is a joinTable of the other two which contains a extra int column named order;

Question

I want to update order with different numbers when I attach songs to Sheets.

But I could only get results with same order.

How can I update Them with different Order via bookshelf.js? or only with loop via knex?

Here is my code

        await new Sheet({sheet_id}).fetch().then(async sheet => {
                let order = 0
                await sheet.songs().attach(song_ids)  //eg. song_ids = [1,2,3,4]
                    .then( async ()=> {
                        sheet.songs().updatePivot({order: order+1},{  
                            query: function (qb){
                                qb.whereIn("song_id", song_ids)
                            }
                        })
                })
        })