Is it possible in access to use the convert function?
AFAIK, there is no such thing - at least not in the manner in which you're referring to. There are conversion functions, but they are solely for converting data types, e.g. numbers to strings, strings to numbers, integers to longs, etc.
This makes no sense to me: "So the convert would have to be converting,Textbox1 and Textbox2 with the Value in Textbox3"
If 1 and 2 are the short version descriptions for a measurement, there is nothing to convert. Nor would I convert the input value in #3 and lose what was there - rather I'd provide the converted value in the textbox I want to show it in (4th) based on what was entered into 3rd.
The 4th could be a bound textbox that could get the necessary formula from a table based on the combo choices, or it could be unbound and you'd programmatically apply the formula. OR in code you could write a whole lot of statements in a Select Case block and again, update the textbox via code. Personally, I'd go with the bound control since one of the main ideas of database design is to minimize code changes when options for an existing feature are added, plus there's no need to write code to control the contents of a textbox when a query can do it. All you'd have to do is add table rows as you expand the conversion feature.
When user clicks your convert button, I'd use a select query that finds the formula in the table where the cmbTo and cmbFrom choices (combos To and From) match the from and to values in the related table fields (I would not use those reserved words). The formula for converting from Celsius to Fahrenheit would look like cmbFrom*9/5+32 and txtResults would be bound to a query that returns the formula. Requery the result control as part of the process and the value should show up IF the formula uses the names of the form controls (cmbFrom or cmbTo or whatever you call them). The table might look like
FromUnits |
ToUnits |
Formula |
Celsius |
Fahrenheit |
cmbFrom*9/5+32 |
Fahrenheit |
Kelvin |
(cmbFrom + 459.67) × 5/9 |
Edit: not sure I agree with extra textboxes just to show short forms. If those need to be shown only during choosing, they could be part of the combo (a second column). If always, labels might make a better choice. I guess it's a matter of design preference.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.