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MS Access Forum / Forms / May 2007saving the value of a calculated field
On a payments form I have (currency) fields for different payments, ie Membership, Pins, Contributions, etc. As I enter the amounts in each field the Total Payment field automatically updates. It works just fine as I enter the individual amounts -- I can see the correct total change on the form; however, the total does not get saved when I close the form. In the table view I can see the individual amounts, but the total is empty. Here's what I have for the Data Control Source for TotalAmount: =[MembershipAmount]+[DecalAmount]+[PinAmount]+[ColectaAmount] What must I do to save the total? Thanks in advance for any help. I appreciate it.  SignaturePosted via a free Usenet account from http://www.teranews.com Dave, You must do nothing at all. It's common sense not to store values from totals. What you do is save the 'operants' and the outcome should be calculated as you did via a textfield or either a field in a query. When using a query you don;t have to look in the table because you don't save the calculation. SignatureMaurice Ausum > On a payments form I have (currency) fields for different payments, ie > Membership, Pins, Contributions, etc. As I enter the amounts in each field [quoted text clipped - 9 lines] > > Thanks in advance for any help. I appreciate it. A calculated control cannot save its data to the table directly because its Control Source is an expression and thus cannot also be a field in the form's underlying RecordSource query/table. So, you'd need to program the form to write the value from the calculated control into the appropriate field of the RecordSource query. Is there a reason you need to store the total amount in the table, though? Can't you just calculate the total from the other fields, thereby negating the need to redundantly store the total? SignatureKen Snell <MS ACCESS MVP> > On a payments form I have (currency) fields for different payments, ie > Membership, Pins, Contributions, etc. As I enter the amounts in each field [quoted text clipped - 9 lines] > > Thanks in advance for any help. I appreciate it. >On a payments form I have (currency) fields for different payments, ie >Membership, Pins, Contributions, etc. As I enter the amounts in each field [quoted text clipped - 7 lines] > >What must I do to save the total? Generally, you should not store calculated values ... what happens if one of the root values change, and (for some reason) the total doesn't get updated? Since you're obviously storing the root values, just calculate the TotalAmount when needed, using the formula you list above. Scott McDaniel scott@takemeout_infotrakker.com www.infotrakker.com >What must I do to save the total? Don't. Storing derived data such as this in your table accomplishes three things: it wastes disk space; it wastes time (almost any calculation will be MUCH faster than a disk fetch); and most importantly, it risks data corruption. If one of the underlying fields is subsequently edited, you will have data in your table WHICH IS WRONG, and no automatic way to detect that fact. Just redo the calculation whenever you need it, either as a calculated field in a Query or just as you're now doing it - in the control source of a Form or a Report textbox. John W. Vinson [MVP] You have received a lot of good advice. Pay particular attention to Johm Vinson. His comment pretty much covers it. I would make one additional comment. Rather than perform the calculation directly in the control source, I would suggest you do it in a public function in a standard module and use the function for the calculation. The reason for this is that you will probably need the calculation in reports or queries and possibly other forms in your application. If you use a function, you can be sure the calculation is always the same regardless of where you call it from. SignatureDave Hargis, Microsoft Access MVP > On a payments form I have (currency) fields for different payments, ie > Membership, Pins, Contributions, etc. As I enter the amounts in each field [quoted text clipped - 9 lines] > > Thanks in advance for any help. I appreciate it. Thanks to you all. I will not save the total. I will not save the total. I will not save the total. Seriously, I appreciate all your input. > On a payments form I have (currency) fields for different payments, ie > Membership, Pins, Contributions, etc. As I enter the amounts in each field [quoted text clipped - 9 lines] > > Thanks in advance for any help. I appreciate it. SignaturePosted via a free Usenet account from http://www.teranews.com >Thanks to you all. > >I will not save the total. >I will not save the total. >I will not save the total. LOL ... so are you sure you won't be saving the total? Good luck with your project! Scott McDaniel scott@takemeout_infotrakker.com www.infotrakker.com >Thanks to you all. > [quoted text clipped - 3 lines] > >Seriously, I appreciate all your input. "Alright, soldiers, cease firing... I think he's waving a white flag..." Sorry for piling on, Dave. John W. Vinson [MVP] |
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