Why do you need to copy the last choice? Does it need to actually be stored in the database? If not I suppose you could grab it using CB Query Field or CB Code Field using either SQL or PHP to parse out the last value. If it needs to be stored you'd also need CB Auto Actions. Aside from that there's no functionality for returning just the last value of a multiselect type field.

webaholic wrote: Hi Krileon & thx for ur reply, i was desperate

the point is that i need to store 5 or 6 last choices for export/report ( i will bought the extention for exporting cb tables).

so i did create a multiselect fields ( instead of chekboxes) ,of course i can export the multiselect values coz they are stored in the DB ..but the pb is that i need to display the last value on the fronted

my question is about the plugins you mention and which one do i need ( for the function i mentionned ) and is it free ? ..if not , h o w m u c h

Kyle mentioned:

CB Query Field:
www.joomlapolis.com/addons/cb-query-field

and CB Code Field:
www.joomlapolis.com/addons/cb-code-field

you can purchase them separately or get them both (and more) as a Professional subscriber:
www.joomlapolis.com/memberships/professional

You need to parse existing code or database values and output the result of that parsing. In other words all of the plugins suggested won't do anything beyond execute the code you tell them to execute. You still need to know how to extract the last value of the multi-checkbox field, which is stored as VALUE1|*|VALUE2|*|VALUE3 in the database, and code it to do that. What you're trying to do however doesn't make a lot of sense and you may want to consider just redoing your fields configuration to better accommodate your needs.