Question 1: Which type of join returns all records when there is a match in either left or right table?

• INNER JOIN
• LEFT JOIN
• RIGHT JOIN
• FULL OUTER JOIN

Question 2: What does the COALESCE function do?

• Combines multiple strings into one
• Returns the first non-NULL value in a list
• Counts the number of NULL values
• Converts data to uppercase

Question 3: Which statement is used to create a stored procedure?

• CREATE PROCEDURE
• MAKE PROCEDURE
• DEFINE PROCEDURE
• NEW PROCEDURE

Question 4: What is the purpose of the UNION operator?

• Combines rows from two tables horizontally
• Combines the result sets of two SELECT statements
• Joins two tables based on a common column
• Creates a backup of a table

Question 5: Which window function assigns a unique rank to each row within its partition?

• ROW_NUMBER()
• RANK()
• DENSE_RANK()
• NTILE()

Question 6: What is a correlated subquery?

• A subquery that returns multiple rows
• A subquery that references columns from the outer query
• A subquery that uses JOIN operations
• A subquery that contains aggregate functions

Question 7: Which operator is used to test for existence of rows in a subquery?

• EXISTS
• IN
• ANY
• ALL

Question 8: What does the WITH clause (Common Table Expression) do?

• Creates a temporary table
• Defines a temporary result set that can be referenced in subsequent queries
• Adds a new column to an existing table
• Creates a database view

Question 9: Which statement is used to create an index on a table?

• CREATE INDEX
• ADD INDEX
• MAKE INDEX
• INDEX TABLE

Question 10: What is the difference between RANK() and DENSE_RANK()?

• RANK() leaves gaps, DENSE_RANK() does not
• DENSE_RANK() leaves gaps, RANK() does not
• They are identical
• RANK() works only with numbers

Question 11: Which SQL statement is used to permanently save changes in a transaction?

• SAVE
• COMMIT
• STORE
• KEEP

Question 12: What is the purpose of the EXPLAIN statement?

• Explains SQL syntax to beginners
• Shows the execution plan of a query
• Describes table structure
• Explains error messages

Question 13: What does ACID stand for in database transactions?

• Atomicity, Consistency, Isolation, Durability
• Accuracy, Consistency, Integrity, Durability
• Atomicity, Consistency, Integrity, Durability
• Accuracy, Completeness, Isolation, Durability

Question 14: Which isolation level allows dirty reads?

• READ COMMITTED
• READ UNCOMMITTED
• REPEATABLE READ
• SERIALIZABLE

Question 15: Which function is used to calculate a running total?

• RUNNING_SUM()
• SUM() with OVER()
• CUMULATIVE_SUM()
• TOTAL_OVER()

Question 16: What is the purpose of the LAG() window function?

• Accesses data from the next row in the same result set
• Accesses data from the previous row in the same result set
• Calculates the difference between current and previous row
• Finds the maximum value in a window

Question 17: Which statement creates a view in SQL?

• CREATE VIEW
• MAKE VIEW
• DEFINE VIEW
• NEW VIEW

Question 18: What does the CASCADE option do in a FOREIGN KEY constraint?

• Automatically deletes/updates related rows in child tables
• Creates multiple foreign keys
• Speeds up query performance
• Allows NULL values in the foreign key

Question 19: Which operator is used for pattern matching with regular expressions?

• LIKE
• MATCH
• REGEXP
• PATTERN

Question 20: What is a self-join?

• A table joined with itself
• A join that doesn't require ON clause
• A join that returns all possible combinations
• A join between two identical tables