Cognizant Sr. Software Engineer interview questions

Round1 One java specific 45 mins test. Not that hard. Round2 What is the difference between Rest and Microservice? Write a Rest code for getting the list of all customers. Suppose this customer is dependent upon various other microservices. Write a code for it. Write a sql query. a. There are 3 tables: table1, table2, table3. Find all those records from table1 which are present in table 2 and table 3 as well. b. There are again 3 tables: table1, table2, table3. Table1 is mapped to table2 and table2 is mapped to table3. Find all those records which are end to end present in table1, table2 and table3. Can we use JOINS for it? LEFT join or inner join? Can we use UNION for it? What is UNION in db? Where do we use it? What is the use of reflections? Where have you used it in your project?

Only one round of interview to get into the company though they advertise 2 rounds. Next round with client that included hacker rank test. Interview round with company was found to be average.