如何在基于交易的库存管理中初始化所有零件的库存？

Question

I have a database that tracks a set of consumable assets and compares on-hand inventory to a forecast of orders for the coming month. It handles finding the on-hand inventory by taking a sum of deposits and withdrawals for each part (when parts are used or new parts are received from a vendor, they are checked in and out).

My gap analysis query takes the input parameters Month and Year and returns the gap between on-hand and forecast. This works great for inventory parts that have already had a transaction on them, but parts that haven't been "initialized" into my transaction table will not appear in the gap analysis.

Is it advisable to just write an append query to add a 0-sum transaction for each part to the transactions table? This seems a little dirty but it may work, but I was wondering if there is a more elegant or best-practice way to do this.

This is my qryGapAnalysis SQL; fair warning, I just use the Access query design so it's disgusting but it may be helpful.

SELECT tblInventory.electrodeID, tblJobs.ForecastYear, 
tblJobs.ForecastMonth, tblJobs.jobNumber, tblJobs.Part, tblJobs.partQty, 
tblInventory.partsPerElectrode, [Qty In]-[Qty Out] AS OnHand, 
IIf(Round(([partQty]/[partsPerElectrode])-Sum([Qty In]-[Qty 
Out]))>0,Round(([partQty]/[partsPerElectrode])-Sum([Qty In]-[Qty Out])),0) 
AS Need
FROM ((tblParts INNER JOIN tblInventory ON tblParts.[Part #] = tblInventory. 
[partID]) INNER JOIN tblJobs ON tblParts.[Part #] = tblJobs.Part) INNER JOIN 
tblTransactions ON tblInventory.electrodeID = tblTransactions.Electrode
GROUP BY tblInventory.electrodeID, tblJobs.ForecastYear, 
tblJobs.ForecastMonth, tblJobs.jobNumber, tblJobs.Part, tblJobs.partQty, 
tblInventory.partsPerElectrode, [Qty In]-[Qty Out], tblInventory.electrodeID
HAVING (((tblJobs.ForecastYear)=Forms!frmGapAnalysisParameters!ComboYear) 
And ((tblJobs.ForecastMonth)=Forms!frmGapAnalysisParameters!ComboMonth));

Answer 1

Try something like this:

select a.electrodeID, b.* from 
    (select b.* from tblParts a INNER JOIN tblInventory b ON tblParts.[Part #] = tblInventory)a 
    left join 
    (SELECT tblInventory.electrodeID, tblJobs.ForecastYear, 
    tblJobs.ForecastMonth, tblJobs.jobNumber, tblJobs.Part, tblJobs.partQty, 
    tblInventory.partsPerElectrode, [Qty In]-[Qty Out] AS OnHand, 
    IIf(Round(([partQty]/[partsPerElectrode])-Sum([Qty In]-[Qty 
    Out]))>0,Round(([partQty]/[partsPerElectrode])-Sum([Qty In]-[Qty Out])),0) 
    AS Need
    FROM ((tblParts INNER JOIN tblInventory ON tblParts.[Part #] = tblInventory. 
    [partID]) INNER JOIN tblJobs ON tblParts.[Part #] = tblJobs.Part) INNER JOIN 
    tblTransactions ON tblInventory.electrodeID = tblTransactions.Electrode
    GROUP BY tblInventory.electrodeID, tblJobs.ForecastYear, 
    tblJobs.ForecastMonth, tblJobs.jobNumber, tblJobs.Part, tblJobs.partQty, 
    tblInventory.partsPerElectrode, [Qty In]-[Qty Out], tblInventory.electrodeID
    HAVING (((tblJobs.ForecastYear)=Forms!frmGapAnalysisParameters!ComboYear) 
    And ((tblJobs.ForecastMonth)=Forms!frmGapAnalysisParameters!ComboMonth))) b on a.electrodeID=b.electrodeID