Modernizing Medicine Interview Question

The interviewer asked easy to moderate Java and Spring boot questions. He asked me questions like String pool, gave me different string variables and asked whether they are equal or not. He also asked me 1 streams, 1 SQL and 1 coding question Java coding - in an array of Integers, find the minimum absolute difference between two integers and print the integers also. SQL - given the customer id from the customer table whose purchase is highest from the purchase table.