John needs to transfer a data set of $50,000$ tuples from database schema$1$ to database schema$2.$ Database schema$1$ contains table$1,$ which has seven attributes and database schema$2$ contains table$2,$ which has five attributes. How will he perform the transfer of the data set of $50,000$ tuples from database schema$1$ to database schema$2$ at the database level? Which fields will be kept, lost, or combined?

Please provide example SQL diagrams and show all design work to support your response. Among all techniques available which one is the most efficient? Why?