update Using values from a form

[Guest]

I have 2 tables, stock and transactions. i want to subtract the value antered
on the form from the UnitsInStock value on the stock table.
how do i get the value from the form.
Currently my query reads;
UPDATE Stock SET UnitsInStock = UnitsInStock-Forms!FrmTransactions!NumOfUnits
WHERE ProductName=forms!FrmTransactions!ProdName;

 

[Steve]

You could create a query that included both your stock and transactions
tables where the query included the field UnitsInStock. You could lock the
UnitsInStock field to prevent data entry or you could make the field not
visible on your form. Then you could put the following code in the Form's
AfterUpdate event;
Me!UnitsInStock = Me!UnitsInStock - Me!NumOfUnits

You put the code in the form's AfterUpdate event so Me!UnitsInStock would
not get changed until you go to a new record or close the form. That way if
an error is made entering NumOfUnits, you can go back and correct the error
without immediately changing UnitsInStock.

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