If your users are inputting a single data value of one field why not make them all access an excel file they edit the row level data and then have a tableau report that is connected to it. So if there is new data you can refresh the data source and tableau will update. Am I understanding your needs right?
Tableau cannot edit the data source it can only read or select data.
I'd like to let the user to choose the items from the list (which can be more than 1000 items) and to input the quantity in order to calculate the line sum.
It can't be by using a excel because in each analysis they would like to choose different items.
Can you reply with an attached Packaged Workbook. I think if we make the right calculated field that can take the users input and we can make it give you the results you are needing. Can you attach some Dummy data for me?
I've a similar issue, where the input would be used to simulate What-if scenarios of employees' salary adjustment, over years, by letting the user type in the % of desired increase directly into some sort of "input" table, on a row by row basis.
I've created the attached dummy data file.
Any help would be appreciated