How to create InventBatchId for an item by Code.

I have table VTVSheetingOrderLine that has 2 fields InventBatchID & ItemId.
And table VTVSheetingOrderLine related to InventDim, InventTrans, InventBatch.
The relations will be like:

InventDim.InventDimId     = InventTrans.InventDimId
InventTrans.InventTransId = VTVSheetingOrderLine .InventTransId
InventDim.InventBatchId  = InventBatch.InventBatchId.

I create form B from table VTVSheetingOrderLine . Add a button "Create Batch Id" on that form.
I wrote codes but it seem not enough, because I don't know how to create the relations between those table

void clicked()
{
    InventNumGroup inventNumGroup;
    Num                     _num;
    int                        increment;
    SalesTable          _salesTable;
    InventTable        _inventTable;
    InventNumGroup            _inventNumGroup;
    NumberSequenceTable   _numberSequenceTable;
    VTVSheetingOrderLine  _vtvSheetingOrderLine;
 ;
   increment =1;
   _inventTable                   = InventTable::find(vtvSheetingOrderLine.ItemId);
   _inventNumGroup          = InventNumGroup::find(_inventTable.BatchNumGroupId);
   _numberSequenceTable = NumberSequenceTable::find(_inventNumGroup.NumberSequenceId);

   if(vtvSheetingOrderLine.ReamId =='')
   {
       _num = NumberSeq::numInsertFormat((_numberSequenceTable.NextRec + increment - 1),_numberSequenceTable.Format);

      ttsbegin;
        select forupdate _numberSequenceTable
       where _numberSequenceTable.NumberSequence == _inventNumGroup.NumberSequenceId;
    if (_numberSequenceTable.InUse == NoYes::No)
        _numberSequenceTable.InUse = NoYes::Yes;
    _numberSequenceTable.NextRec += increment;
    _numberSequenceTable.update();

    vtvSheetingOrderLine.InventBatchId= _num;
    vtvSheetingOrderLine.update();
ttscommit;

   vtvSheetingOrderLine_ds.reread();
   vtvSheetingOrderLine_ds.refresh();
   vtvSheetingOrderLine_ds.research();
  }
// super();
}

I don't know how to filled almost fields of InventTrans, InventDim,InventBatch.

How can I create InventBatchID by Code with the relation structure like above following to the standard way that Microsoft Dynamic AX has done - the way AX create InventBatchID for an Item:

Purchase Order Details -> create Purchase Lines -> Inventory -> Registration -> click Auto create -> Post all -> inventBatchId of an Item is created.
====
InventBatchId in InventDim table gets updated through -

1) InventUpdate class -> writeInventTransAutoDim method and
2) Classes extended from InventUpdate (example - InventUpd_Arrived, InventUpd_Estimated etc)

Essentially InventUpdate class is the engine which updates inventory transactions.
=====
Sorry I misinterpreted your query. If you want to create inventBatchId by code, you can follow any approach from below -

1) InventDim table -> findOrCreate method. Basically here, you create a buffer of InventDim table and call this method. If contents in this buffer doesn't exist, new record will be created.

2) InventDim table -> find method. This is similar to the above. But here you check with InventDim id. If it doesn't exist, then you will have to manually call 'insert' method in 'InventDim' table. For example - see 'prepareForSave' method in 'AxdItem' class.
=======
In your scenario, you actually need to create a new record in InventBatch table and use the method InventDim::findOrCreate to create a new record in InventDim table, then use the InventDimId of the new record to link to your transaction table.

This is exactly what you descrived above with the purchase order. When you create a PO line --> AX create new inventTrans record, then when you register new batch number, it create InventDim record.

Secondly, to know how AX create record in InventTransTable, take a look into method createLine() of SalesLine table or PurchLine table.
========