Practice SQL Questions and Answers

• What is the output of this SQL snippet if the price column contains NULL values? SELECT SUM(price) FROM products;
• Which SQL command is used to remove a table completely?
• Which SQL clause is used for filtering rows?
• Which SQL function returns the number of rows in a table?
• Which SQL clause is used to group rows?
• Which command removes all rows but keeps table structure?
• Which SQL keyword prevents duplicate rows in result?
• Which SQL feature allows hierarchical queries (e.g., org chart traversal)?
• In SQL, the ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW clause applies to:
• A materialized view differs from a normal view because it:
• Recursive CTEs are mainly used for:
• ROW_NUMBER() OVER (PARTITION BY dept ORDER BY salary DESC) assigns:
• Materialized views differ from normal views because:
• Which SQL keyword removes duplicate rows automatically from results?
• Which operator is used for pattern matching in SQL?
• What is the result of SELECT COUNT(NULL) on any table?
• To rename a column in a SELECT query result, you use:
• Which SQL constraint ensures a column cannot have NULL values?
• Which SQL constraint ensures that a column’s values are unique across the table?
• A transaction in DBMS is said to be atomic if:
• Which of the following is true about a foreign key?
• In normalization, which normal form removes transitive dependencies?
• Deadlock in DBMS can be prevented using:
• Which SQL keyword is used to eliminate duplicate rows in a query result?
• Which SQL function is used to calculate the average of a numeric column?
• Which SQL clause is used to filter results after a GROUP BY operation?
• Which SQL statement combines the results of two queries and removes duplicates?
• Which SQL function returns the largest value in a column?
• Which SQL command is used to modify existing records in a table?
• Which clause is used to sort query results in SQL?
• Which SQL operator is used to search for a pattern in a column?
• Which SQL keyword is used to remove duplicate records from a query result?
• Which SQL clause is used to filter records based on aggregate functions?
• Which operator is used to combine results of two SELECT queries and remove duplicates?
• SQL Injection can be prevented by all EXCEPT:
• Which SQL clause is used to filter groups after aggregation (i.e., having aggregated value conditions)?
• Given a table employees(id, dept_id, salary), which query returns departments with average salary greater than overall average across the company?
• Which of the following SQL constructs avoids returning duplicate rows?
• Which join returns rows from the left table even when there is no matching row in the right table, filling with NULLs for the right side?
• Which index type is most beneficial for queries that use range predicates (e.g., WHERE age BETWEEN 20 AND 30)?