Test Your PostgreSQL IN Operator Knowledge with This Quiz

Progress

True / False

In PostgreSQL, the IN keyword is used to specify multiple possible values for a column.

True False

The IN keyword is used to filter rows where the column's value matches any value in a specified list.

True / False

In PostgreSQL, the IN keyword can be used with numeric values only.

True False

The IN keyword can be used with numeric, text, date, and other data types.

True / False

In PostgreSQL, the IN keyword is case-sensitive when used with text values.

True False

PostgreSQL's IN keyword is case-sensitive when comparing text values, just like other SQL comparisons.

True / False

In PostgreSQL, using NOT IN will return rows where the column's value does not match any value in the specified list.

True False

NOT IN filters rows where the column's value does not match any value in the specified list.

True / False

In PostgreSQL, the IN keyword can be used with subqueries to specify a dynamic list of values.

True False

The IN keyword can be used with subqueries, allowing for dynamic value lists based on the result of the subquery.

True / False

In PostgreSQL, the IN keyword can be used with empty lists without causing an error.

True False

Using the IN keyword with an empty list will not cause an error but will always return false, resulting in no rows being returned.

True / False

In PostgreSQL, using the IN keyword with a large list of values can impact query performance.

True False

A large list of values in an IN clause can degrade query performance, especially if the list is not indexed or optimized.

True / False

In PostgreSQL, the IN keyword can be used within a JOIN condition.

True False

The IN keyword can be used within a JOIN condition to match rows based on a list of values.

True / False

In PostgreSQL, the IN keyword can be combined with other logical operators like AND and OR.

True False

The IN keyword can be combined with logical operators to create complex filtering conditions.

Q10

True / False

In PostgreSQL, using the IN keyword with a subquery that returns NULL will return rows where the column value is NULL.

True False

If a subquery used with IN returns NULL, the IN condition will not match any rows, as NULL comparisons always result in unknown in SQL.

Q11

Single Choice

Which of the following SQL statements will correctly use the IN operator to find employees who are either 'Manager' or 'Developer' in PostgreSQL?

SQL Code

SELECT name
FROM employees
WHERE job_title IN ('Manager', 'Developer');

SELECT name FROM employees WHERE job_title = 'Manager' AND job_title = 'Developer'; SELECT name FROM employees WHERE job_title IN ('Manager', 'Developer'); SELECT name FROM employees WHERE job_title NOT IN ('Manager', 'Developer');SELECT name FROM employees WHERE job_title IS NULL;

The IN operator is used to check if a value matches any value in a list of values. Option B is the correct syntax for this purpose in PostgreSQL.

Q12

Single Choice

What does the following SQL query return in PostgreSQL?

SQL Code

SELECT *
FROM students
WHERE grade IN (85, 90, 95);

Students with grades higher than 95 Students with grades lower than 85 Students with grades equal to 85, 90, or 95All students

The IN operator checks if the grade value is equal to any of the values in the list (85, 90, 95). Option C is the correct interpretation.

Q13

Single Choice

In PostgreSQL, which statement is true about the IN operator?

It can only be used with numeric values. It is case-insensitive It is used to match a value against a set of valuesIt can only be used in subqueries

The IN operator is used to match a value against a set of values, making option C the correct answer.

Q14

Single Choice

How does the IN operator behave in PostgreSQL when used with NULL values?

SQL Code

SELECT *
FROM products
WHERE product_id IN (1, 2, NULL);

It will ignore the NULL value. It will return an error. It will return rows where product_id is NULLIt will return no rows if product_id is NULL.

In PostgreSQL, the IN operator will ignore the NULL value in the list and only compare against non-null values.

Q15

Single Choice

Given the following query in PostgreSQL, what will be the result if the list contains a NULL?

SQL Code

SELECT name
FROM customers
WHERE city IN ('New York', 'Los Angeles', NULL);

It will return names from cities 'New York' and 'Los Angeles' and exclude NULL. It will throw an error It will return only NULL valuesIt will return all rows in the table

The IN operator in PostgreSQL ignores the NULL value, so only 'New York' and 'Los Angeles' are considered.

Q16

Single Choice

Which SQL query correctly uses the IN operator to filter rows in PostgreSQL?

SQL Code

SELECT department
FROM departments
WHERE department_id IN (SELECT department_id FROM employees WHERE salary > 50000);

SELECT department FROM departments WHERE department_id = (SELECT department_id FROM employees WHERE salary > 50000); SELECT department FROM departments WHERE department_id NOT IN (SELECT department_id FROM employees WHERE salary > 50000) SELECT department FROM departments WHERE department_id IN (SELECT department_id FROM employees WHERE salary > 50000);SELECT department FROM departments WHERE department_id IS NULL;

The IN operator is correctly used to filter rows based on a subquery that returns multiple department IDs where employees have a salary greater than 50000.

Q17

Single Choice

Consider the following SQL query. What will it return in PostgreSQL?

SQL Code

SELECT employee_id
FROM employees
WHERE department_id NOT IN (SELECT department_id FROM departments WHERE location = 'New York');

Employees in departments located in New York Employees in departments not located in New York Employees with NULL department IDsAll employees

The NOT IN operator returns employees whose department_id does not match any department_id located in New York.

Q18

Single Choice

What is the result of using the IN operator in the following PostgreSQL query with a large list of values?

SQL Code

SELECT order_id
FROM orders
WHERE customer_id IN (1, 2, 3, ..., 10000);

It will cause a syntax error. It will execute faster than using multiple OR conditions. It may cause performance issues if the list is too large.It will always be slower than using a JOIN

While the IN operator is efficient, using it with a very large list can cause performance issues in PostgreSQL.

Q19

Single Choice

Which of the following queries will return all rows from the sales table where the region is either 'North' or 'South' using the IN operator in PostgreSQL?

SQL Code

SELECT *
FROM sales
WHERE region IN ('North', 'South');

SELECT * FROM sales WHERE region = 'North' OR region = 'South'; SELECT * FROM sales WHERE region IN ('North', 'South'); SELECT * FROM sales WHERE region NOT IN ('North', 'South');SELECT * FROM sales WHERE region IS NULL;

The IN operator in PostgreSQL is used to match the region value against 'North' and 'South', so option B is the correct answer.

Q20

Single Choice

In PostgreSQL, when using the IN operator with a subquery, which of the following scenarios will lead to unexpected results?

SQL Code

SELECT product_id
FROM products
WHERE category_id IN (SELECT category_id FROM categories WHERE status IS NULL);

When the subquery returns NULL values When the subquery returns an empty set When the main query has a NULL in the listNone of the above

If the subquery returns NULL values, the IN operator may lead to unexpected results because NULL comparisons can cause certain rows to be excluded.

Q21

Multiple Choice

Identify the SQL scripts that correctly use the IN operator to filter numeric values in PostgreSQL.

SELECT * FROM employees WHERE department_id IN (1, 2, 3); SELECT * FROM employees WHERE department_id = 1 OR department_id = 2 OR department_id = 3; SELECT * FROM employees WHERE department_id IN ('1', '2', '3');SELECT * FROM employees WHERE department_id IN (1 AND 2 AND 3);

The IN operator is used to filter the result set by matching a list of values. The correct scripts will demonstrate how to use the IN operator with numeric values in PostgreSQL.

Q22

Multiple Choice

Select the SQL scripts that correctly use the IN operator with string values in PostgreSQL.

SELECT * FROM customers WHERE state IN ('CA', 'NY', 'TX'); SELECT * FROM customers WHERE state = 'CA' OR state = 'NY' OR state = 'TX'; SELECT * FROM customers WHERE state IN (CA, NY, TX);SELECT * FROM customers WHERE state IN ('CA' AND 'NY' AND 'TX');

The IN operator can be used to filter string values based on a list of specific values. The correct scripts will demonstrate how to use the IN operator with string values in PostgreSQL.

Q23

Multiple Choice

Determine the SQL scripts that correctly use the IN operator with subqueries in PostgreSQL.

SELECT * FROM employees WHERE department_id IN (SELECT department_id FROM departments WHERE location_id = 10); SELECT * FROM employees WHERE department_id = ANY (SELECT department_id FROM departments WHERE location_id = 10); SELECT * FROM employees WHERE department_id IN (SELECT department_id FROM departments WHERE location_id = 10 AND department_id IS NOT NULL);SELECT * FROM employees WHERE department_id IN (SELECT department_id FROM departments WHERE location_id = 10) AND department_id IS NOT NULL;

The IN operator can be used with subqueries to filter based on the results of another query. The correct scripts will demonstrate how to use the IN operator with subqueries in PostgreSQL.

Q24

Multiple Choice

Identify the SQL scripts that correctly use the IN operator with NOT in PostgreSQL.

SELECT * FROM employees WHERE department_id NOT IN (4, 5, 6); SELECT * FROM employees WHERE department_id <> 4 AND department_id <> 5 AND department_id <> 6; SELECT * FROM employees WHERE department_id NOT IN ('4', '5', '6');SELECT * FROM employees WHERE NOT department_id IN (4, 5, 6);

The NOT IN operator is used to exclude rows that match a list of values. The correct scripts will demonstrate how to use the NOT IN operator in PostgreSQL.

Q25

Multiple Choice

Select the SQL scripts that correctly use the IN operator with JOINs in PostgreSQL.

SELECT o.*, c.customer_name FROM orders o JOIN customers c ON o.customer_id = c.customer_id WHERE o.customer_id IN (101, 102, 103); SELECT o.*, c.customer_name FROM orders o JOIN customers c ON o.customer_id = c.customer_id WHERE c.customer_id IN (101, 102, 103); SELECT o.*, c.customer_name FROM orders o JOIN customers c ON o.customer_id = c.customer_id WHERE o.customer_id = 101 OR o.customer_id = 102 OR o.customer_id = 103;SELECT o.*, c.customer_name FROM orders o JOIN customers c ON o.customer_id = c.customer_id WHERE o.customer_id IN (101 AND 102 AND 103);

The IN operator can be used with JOINs to filter results from multiple tables based on a list of values. The correct scripts will demonstrate how to use the IN operator with JOINs in PostgreSQL.

Q26

Multiple Choice

Determine the SQL scripts that correctly use the IN operator with multiple columns in PostgreSQL.

SELECT * FROM orders WHERE (customer_id, product_id) IN (SELECT customer_id, product_id FROM order_details); SELECT * FROM orders WHERE customer_id IN (SELECT customer_id FROM order_details) AND product_id IN (SELECT product_id FROM order_details); SELECT * FROM orders WHERE (customer_id, product_id) = ANY (SELECT customer_id, product_id FROM order_details);SELECT * FROM orders WHERE (customer_id, product_id) IN (SELECT customer_id, product_id FROM order_details WHERE customer_id IS NOT NULL);

The IN operator can be used with multiple columns by combining columns in a subquery. The correct scripts will demonstrate how to use the IN operator with multiple columns in PostgreSQL.

Q27

Multiple Choice

Identify the SQL scripts that correctly use the IN operator with EXISTS in PostgreSQL.

SELECT * FROM products WHERE product_id IN (SELECT product_id FROM order_details WHERE EXISTS (SELECT 1 FROM orders WHERE orders.order_id = order_details.order_id)); SELECT * FROM products WHERE EXISTS (SELECT 1 FROM order_details WHERE order_details.product_id = products.product_id); SELECT * FROM products WHERE product_id IN (SELECT product_id FROM order_details);SELECT * FROM products WHERE product_id = ANY (SELECT product_id FROM order_details WHERE EXISTS (SELECT 1 FROM orders WHERE orders.order_id = order_details.order_id));

The IN operator can be combined with EXISTS to filter based on the existence of rows in a subquery. The correct scripts will demonstrate how to use the IN operator with EXISTS in PostgreSQL.

Q28

Multiple Choice

Select the SQL scripts that correctly use the IN operator with window functions in PostgreSQL.

SELECT employee_id, department_id, RANK() OVER (PARTITION BY department_id ORDER BY salary DESC) AS rank FROM employees WHERE department_id IN (1, 2, 3); SELECT employee_id, department_id, DENSE_RANK() OVER (PARTITION BY department_id ORDER BY salary DESC) AS rank FROM employees WHERE department_id IN (1, 2, 3); SELECT employee_id, department_id, ROW_NUMBER() OVER (PARTITION BY department_id ORDER BY salary DESC) AS rank FROM employees WHERE department_id IN (1, 2, 3);SELECT employee_id, department_id, RANK() OVER (PARTITION BY department_id ORDER BY salary DESC) AS rank FROM employees WHERE department_id IN (1, 2, 3, 4);

The IN operator can be used with window functions to filter and rank results within specific partitions. The correct scripts will demonstrate how to use the IN operator with window functions in PostgreSQL.

Q29

Multiple Choice

Determine the SQL scripts that correctly use the IN operator with UNION in PostgreSQL.

SELECT employee_id, department_id FROM employees WHERE department_id IN (10, 20, 30) UNION SELECT contractor_id, department_id FROM contractors WHERE department_id IN (10, 20, 30); SELECT employee_id, department_id FROM employees WHERE department_id = ANY (10, 20, 30) UNION SELECT contractor_id, department_id FROM contractors WHERE department_id = ANY (10, 20, 30); SELECT employee_id, department_id FROM employees WHERE department_id IN (10, 20, 30) UNION SELECT contractor_id, department_id FROM contractors WHERE department_id IN (10, 20);SELECT employee_id, department_id FROM employees WHERE department_id IN (10, 20, 30) UNION ALL SELECT contractor_id, department_id FROM contractors WHERE department_id IN (10, 20, 30);

The IN operator can be used with UNION to filter and combine results from multiple tables. The correct scripts will demonstrate how to use the IN operator with UNION in PostgreSQL.

Q30

Multiple Choice

Identify the SQL scripts that correctly use the IN operator with DISTINCT in PostgreSQL.

SELECT DISTINCT department_id FROM employees WHERE location_id IN (100, 200, 300); SELECT DISTINCT department_id FROM employees WHERE location_id = ANY (100, 200, 300); SELECT department_id FROM (SELECT DISTINCT department_id FROM employees) AS sub WHERE location_id IN (100, 200, 300);SELECT DISTINCT department_id FROM employees WHERE location_id IN ('100', '200', '300');

The IN operator can be used with DISTINCT to filter unique rows based on a list of values. The correct scripts will demonstrate how to use the IN operator with DISTINCT in PostgreSQL.

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