Increment/Decrement Inventory Values

Inventory Database Calculations Example

Custom Inventory software is the most widely requested type database for our programmers. In this Access database example download we demonstrate the simplest method for calculating inventory totals when creating purchase order or similar Access forms.  This Access database download shows how you can use the Docmd.Runsql statement in the after update (afterupdate) event to increment and decrement inventory totals. The methods demonstrated here are only suitable for single-user database systems since the code does not take into account the possibility of locked table records.

The following code is run from the Access database example:

Option Compare Database
Public hold_qty As Long

Private Sub Qty_Out_AfterUpdate()
DoCmd.RunSQL "Update M_Inventory set inv_qty=inv_qty+" & Nz(hold_qty, 0) & " where barcode=" & Me.BarCode
DoCmd.RunSQL "Update M_Inventory set inv_qty=inv_qty-" & Nz(Me.Qty_Out, 0) & " where barcode=" & Me.BarCode
Me.QOH.Requery
End Sub

Private Sub Qty_Out_Enter()
hold_qty = Me.Qty_Out
End Sub

The inventory calculations method shown in this example should only be considered for a one-user inventory system.  Consider using transaction processing for these types of calculations in a multi-user database so that record locking and update failures can be tracked to increase database integrity and inventory calculation accuracy.  Download the Access 2000 Inventory Calculations Example.