Keep relationships for not only business but personal, which shoots successful business development. Do you agree?

Yes. Personal relationship builds trust & faith among the colleagues which gears up the cooperation & understanding among the team members to set for one direction.

Its depends on customer behavior some customer needs to have personal relationship and some don't. you can get more business with small efforts if  you have good relationship with customer.

Absolutely not. Personal relationship can greatly damage business relationship.  In order to keep work ethics and fairness in business, you must have a straight forward relationship with others regardless of who they are. One of the most negative impacts on business is favoritism.

True regarded been growing trade relations with personal relationships and helping to boom business growth and be benefit for all

Building rapport personally and business related is good as relationship can help you get access to organization for sales and marketing/business development.  Even sometimes it helps because of network to get into job which do you expect as they know your capabilites