Lookup field not updating when the document uploading

Question

I am uploading document programically and passing lookup field value but its not get updated, how to handle this?

Answer 1

For a lookup column you must provide the ID of the item you are referring to.

Thus if the item being lookup has an ID of 3 you must provide that in the hashtable, with lookups to multiple items you must provide the ID and the value separeted by ;# e.g.: 1;#First Item;#3;#THirdItem.

Answer 2

You need have to update the SPList object...