Hi ,

I have a two objects 1.Candidate__c 2.Book__c.

Book is the child object  for Candidate. we can create a book records through candidate related list.

Book is having picklist field i.e "Book_Name__c". Book_name__c having only one value Java but while creating a book record by default None will be displayed for this field.

Now i have created a Book record with Book_Name__c= Java through candidate related list.

My question is :

If i create another book record  with Book_Name__c= Java through candidate related list then i need to make previously created record field Book_Name__c is blank(null)

i need to achieve the above requirement through trigger only. Can you please help me on this?

I don't know coding pls help me!!

Thanks in advance