Database (DBMS) - MCQ Practice Questions

In a student enrollment database, you need to find students enrolled in multiple courses. Which JOIN type should be used to match course_id from enrollment table with course table?

What is the default sort order for ORDER BY clause in SQL?

Which aggregate function ignores NULL values in SQL?

In a bank database with accounts and transactions tables, to find accounts with transactions greater than 100,000, which clause must follow GROUP BY?

What will be the result of: SELECT $\frac{10}{3}$ in SQL?

A company table has 500K employee records. To find employees with salary > 50,000 efficiently, which strategy is optimal?

Which SQL statement is used to add a new column to existing table?

For a sales database, to get top 5 products by revenue in each region, which window function approach is suitable?

In an e-commerce platform with orders table, which index structure is best for frequently filtering by customer_id AND order_date?

Which of the following is a valid correlated subquery for finding employees earning more than their department average?

For a student result database, to calculate cumulative marks from beginning of year, which window function is appropriate?

In a bank database with accounts table, which query correctly identifies dormant accounts (no transactions in 2 years)?

Which anomaly in unnormalized database allows insertion of duplicate partial information without main entity?

For optimizing a complex query joining 5 tables with WHERE conditions, what is the recommended approach?

In a manufacturing database, to find products with sales in ALL regions, which approach is correct?

Which feature of SQL allows preventing duplicate values in a column?

For a multi-million row analytics database, which data type is most storage-efficient for storing yes/no values?