Tata Consultancy Services Data Engineer interview questions

SQL and Databases What is the difference between OLTP and OLAP systems? How would you optimize a slow SQL query? Explain the concepts of primary key, foreign key, and unique key. Write a query to find duplicate records in a table. How do you handle NULL values in SQL? What are indexes, and how do they impact query performance? What is a transaction, and how does ACID compliance ensure data integrity