I have a dbf with a field named "ppa" .the type of ppa is double. users enter number (for example 0.023) in a textbox and select the dbf in a combobox . then click Run and program multiply 0.023 with each number of ppa and save the result in another field . what objects do i need for programming ? How can i do this ?
All you would do is set up your parameters (input table, input float value) and set up Calculate Field in the script/model to use the entered parameters, then double-click the tool/model from ArcToolbox to bring up the user interface, enter the values and click OK. About as simple as it gets really.
Also, if you run the tool/model from an MXD containing tables, it will automatically populate the input table parameter dropdown box with a list of available tables in the document.