[Koha] Call sql query

I have a library database in which half of the records are pre Koha 3.x. When the conversion was done from 2.x to 3.x, none of the call numbers ended up in the Items data field. What I am looking for is an sql query to extract the call numbers from the biblio call number field and insert same in the corresponding item(s) record for that specific biblio item. I'm trying to avoid having to manually edit all of the items to insert the call numbers. Any help would be greatly appreciated. SKA man