Test Your PostgreSQL ORDER BY Command Knowledge with This Quiz

Progress

True / False

In PostgreSQL, the ORDER BY clause is used to sort the result set.

True False

The ORDER BY clause sorts the result set based on one or more columns.

True / False

In PostgreSQL, the ORDER BY clause sorts the result set in ascending order by default.

True False

By default, ORDER BY sorts the result set in ascending order.

True / False

In PostgreSQL, the ORDER BY clause must always be used with the LIMIT clause.

True False

The ORDER BY clause can be used independently to sort the result set and does not require the LIMIT clause.

True / False

In PostgreSQL, the ORDER BY clause can sort the result set by multiple columns.

True False

The ORDER BY clause can sort the result set by multiple columns, specifying the sort order for each column.

True / False

In PostgreSQL, the ORDER BY clause can use column aliases defined in the SELECT statement.

True False

Column aliases defined in the SELECT statement can be used in the ORDER BY clause to sort the result set.

True / False

In PostgreSQL, you cannot use ORDER BY with expressions or functions.

True False

The ORDER BY clause can use expressions or functions to determine the sort order of the result set.

True / False

In PostgreSQL, using ORDER BY with a large dataset can impact query performance.

True False

Sorting a large dataset using ORDER BY can be resource-intensive and impact query performance, especially if indexes are not used.

True / False

In PostgreSQL, the ORDER BY clause can sort null values first or last by using NULLS FIRST or NULLS LAST.

True False

The NULLS FIRST and NULLS LAST options can be used with ORDER BY to specify the placement of null values in the sorted result set.

True / False

In PostgreSQL, the ORDER BY clause can be used in subqueries and window functions.

True False

The ORDER BY clause can be used within subqueries and window functions to control the order of rows processed or returned.

Q10

True / False

In PostgreSQL, using the ORDER BY clause with DISTINCT in a query requires the columns in ORDER BY to be included in the DISTINCT clause.

True False

When using ORDER BY with DISTINCT, the columns specified in ORDER BY must also be included in the DISTINCT clause to ensure a valid query syntax and consistent results.

Q11

Single Choice

Which keyword is used to sort the result set in ascending order by default in PostgreSQL?

DESC ASC ORDERSORT

In PostgreSQL, the ORDER BY clause is used to sort the result set by one or more columns. By default, it sorts in ascending order.

Q12

Single Choice

What is the default sorting order when using the ORDER BY clause in PostgreSQL?

Ascending Descending RandomBased on index

In PostgreSQL, when no order is specified in the ORDER BY clause, the result set is sorted in ascending order by default.

Q13

Single Choice

How do you sort the result set by multiple columns in PostgreSQL?

ORDER BY column1, column2 SORT BY column1 AND column2 GROUP BY column1, column2ALIGN BY column1 THEN column2

In PostgreSQL, you can sort by multiple columns by specifying them separated by commas in the ORDER BY clause.

Q14

Single Choice

Given the table employees(name TEXT, salary INTEGER), which query will return the list of employees sorted by salary in descending order?

SELECT name FROM employees ORDER BY salary ASC; SELECT name FROM employees ORDER BY salary; SELECT name FROM employees ORDER BY salary DESC;SELECT name FROM employees ORDER BY salary DESCENDING;

The DESC keyword is used in PostgreSQL to sort the result set in descending order.

Q15

Single Choice

How would you modify the following query to also sort by name in ascending order when salaries are equal?

SQL Code

SELECT name, salary FROM employees ORDER BY salary DESC;

SELECT name, salary FROM employees ORDER BY salary DESC, name ASC; SELECT name, salary FROM employees ORDER BY salary DESC AND name ASC; SELECT name, salary FROM employees GROUP BY salary DESC, name ASC;SELECT name, salary FROM employees ORDER BY salary DESC THEN name ASC;

In PostgreSQL, multiple columns can be used in the ORDER BY clause by separating them with commas, with each column’s sorting order specified.

Q16

Single Choice

What will be the output order of the following query?

SQL Code

SELECT name, age FROM students ORDER BY 2 DESC;

Sorted by name in descending order Sorted by age in descending order Sorted by name in ascending orderSorted by age in ascending order

In PostgreSQL, the ORDER BY 2 DESC clause sorts the result set by the second column (in this case, age) in descending order.

Q17

Single Choice

Given the table products(name TEXT, category TEXT, price NUMERIC), which query will return all products sorted first by category in ascending order, and then by price in descending order?

SELECT name FROM products ORDER BY category ASC, price ASC; SELECT name FROM products ORDER BY category, price DESC; SELECT name FROM products ORDER BY category DESC, price ASC;SELECT name FROM products ORDER BY category DESC, price DESC;

The ORDER BY category, price DESC clause sorts first by category in ascending order (the default) and then by price in descending order.

Q18

Single Choice

In PostgreSQL, which query will sort the employees table by salary in ascending order and display only the top 5 highest salaries?

SQL Code

SELECT * FROM employees ORDER BY salary ASC LIMIT 5;

SELECT * FROM employees ORDER BY salary DESC LIMIT 5; SELECT * FROM employees ORDER BY salary ASC LIMIT 5; SELECT * FROM employees ORDER BY salary LIMIT 5;SELECT * FROM employees ORDER BY salary DESC;

The query sorts employees by salary in ascending order and limits the result set to the top 5 rows.

Q19

Single Choice

How do you ensure that NULL values appear at the end of the result set when using ORDER BY in PostgreSQL?

SQL Code

SELECT name, salary FROM employees ORDER BY salary;

SELECT name, salary FROM employees ORDER BY salary NULLS LAST; SELECT name, salary FROM employees ORDER BY salary IS NOT NULL; SELECT name, salary FROM employees ORDER BY salary DESC;SELECT name, salary FROM employees ORDER BY salary NULLS FIRST;

The NULLS LAST option in PostgreSQL ensures that NULL values appear at the end of the result set.

Q20

Single Choice

Which of the following queries correctly orders a list of products by price in descending order, but only for those products in the 'Electronics' category, with any NULL prices appearing last?

SELECT name, price FROM products WHERE category = 'Electronics' ORDER BY price NULLS LAST; SELECT name, price FROM products WHERE category = 'Electronics' ORDER BY price DESC NULLS LAST; SELECT name, price FROM products WHERE category = 'Electronics' ORDER BY price DESC, NULLS LAST;SELECT name, price FROM products WHERE category = 'Electronics' ORDER BY price DESCENDING, NULLS LAST;

This query filters the products table by category and orders the results by price in descending order with NULL values appearing last in the list.

Q21

Multiple Choice

Identify the SQL scripts that correctly perform a basic ORDER BY operation in PostgreSQL.

SELECT * FROM employees ORDER BY last_name ASC; SELECT * FROM employees ORDER BY last_name; SELECT * FROM employees ORDER BY last_name DESC;SELECT * FROM employees ORDER BY first_name ASC;

The ORDER BY clause is used to sort the result set in either ascending or descending order. The correct scripts will demonstrate how to use ORDER BY with a single column in PostgreSQL.

Q22

Multiple Choice

Select the SQL scripts that correctly perform an ORDER BY operation on multiple columns in PostgreSQL.

SELECT * FROM employees ORDER BY department_id ASC, last_name DESC; SELECT * FROM employees ORDER BY department_id, last_name DESC; SELECT * FROM employees ORDER BY department_id ASC, last_name ASC;SELECT * FROM employees ORDER BY department_id DESC, last_name ASC;

ORDER BY can be applied to multiple columns to sort the data first by one column and then by another. The correct scripts will demonstrate how to use ORDER BY on multiple columns in PostgreSQL.

Q23

Multiple Choice

Determine the SQL scripts that correctly perform an ORDER BY operation with NULLS FIRST in PostgreSQL.

SELECT * FROM employees ORDER BY salary ASC NULLS FIRST; SELECT * FROM employees ORDER BY salary NULLS FIRST; SELECT * FROM employees ORDER BY salary ASC, NULLS FIRST;SELECT * FROM employees ORDER BY salary DESC NULLS FIRST;

The NULLS FIRST option can be used with ORDER BY to place NULL values at the beginning of the result set. The correct scripts will demonstrate how to use ORDER BY with NULLS FIRST in PostgreSQL.

Q24

Multiple Choice

Identify the SQL scripts that correctly perform an ORDER BY operation with LIMIT in PostgreSQL.

SELECT * FROM employees ORDER BY salary DESC LIMIT 5; SELECT * FROM employees LIMIT 5 ORDER BY salary DESC; SELECT * FROM employees ORDER BY salary DESC LIMIT 5 OFFSET 0;SELECT * FROM employees LIMIT 5 ORDER BY salary ASC;

LIMIT can be combined with ORDER BY to retrieve a specific number of rows after sorting. The correct scripts will demonstrate how to use ORDER BY with LIMIT in PostgreSQL.

Q25

Multiple Choice

Select the SQL scripts that correctly perform an ORDER BY operation with JOINs in PostgreSQL.

SELECT o.*, c.customer_name FROM orders o JOIN customers c ON o.customer_id = c.customer_id ORDER BY o.order_date ASC, c.customer_name DESC; SELECT o.*, c.customer_name FROM orders o JOIN customers c ON o.customer_id = c.customer_id ORDER BY order_date ASC, customer_name DESC; SELECT o.*, c.customer_name FROM orders o LEFT JOIN customers c ON o.customer_id = c.customer_id ORDER BY order_date ASC, customer_name ASC;SELECT * FROM orders o JOIN customers c ON o.customer_id = c.customer_id ORDER BY o.order_date ASC, c.customer_name DESC;

JOINs can be combined with ORDER BY to sort data from multiple tables. The correct scripts will demonstrate how to use ORDER BY with JOINs in PostgreSQL.

Q26

Multiple Choice

Determine the SQL scripts that correctly perform an ORDER BY operation with window functions in PostgreSQL.

SELECT *, RANK() OVER (PARTITION BY department_id ORDER BY salary DESC) AS rank FROM employees ORDER BY department_id ASC, salary DESC; SELECT *, RANK() OVER (ORDER BY salary DESC) AS rank FROM employees ORDER BY department_id ASC, salary DESC; SELECT *, DENSE_RANK() OVER (PARTITION BY department_id ORDER BY salary DESC) AS rank FROM employees ORDER BY department_id ASC, salary DESC;SELECT *, ROW_NUMBER() OVER (PARTITION BY department_id ORDER BY salary DESC) AS rank FROM employees ORDER BY department_id ASC, salary DESC;

Window functions can be used with ORDER BY to rank or perform other calculations across a subset of rows. The correct scripts will demonstrate how to use window functions with ORDER BY in PostgreSQL.

Q27

Multiple Choice

Identify the SQL scripts that correctly perform an ORDER BY operation with GROUP BY in PostgreSQL.

SELECT department_id, SUM(amount) AS total_sales FROM sales GROUP BY department_id ORDER BY total_sales DESC; SELECT department_id, SUM(amount) AS total_sales FROM sales GROUP BY department_id ORDER BY department_id DESC; SELECT department_id, SUM(amount) AS total_sales FROM sales GROUP BY department_id ORDER BY SUM(amount) DESC;SELECT department_id, SUM(amount) AS total_sales FROM sales GROUP BY department_id HAVING SUM(amount) > 1000 ORDER BY total_sales DESC;

GROUP BY can be used with ORDER BY to sort the grouped data. The correct scripts will demonstrate how to use ORDER BY with GROUP BY in PostgreSQL.

Q28

Multiple Choice

Select the SQL scripts that correctly perform an ORDER BY operation with DISTINCT in PostgreSQL.

SELECT DISTINCT customer_id FROM orders ORDER BY order_date ASC; SELECT DISTINCT ON (customer_id) * FROM orders ORDER BY order_date ASC; SELECT customer_id FROM orders GROUP BY customer_id ORDER BY order_date ASC;SELECT DISTINCT customer_id FROM orders ORDER BY order_date DESC;

DISTINCT can be used with ORDER BY to retrieve and sort unique rows. The correct scripts will demonstrate how to use ORDER BY with DISTINCT in PostgreSQL.

Q29

Multiple Choice

Determine the SQL scripts that correctly perform an ORDER BY operation with OFFSET in PostgreSQL.

SELECT * FROM transactions ORDER BY transaction_date DESC LIMIT 10 OFFSET 10; SELECT * FROM transactions ORDER BY transaction_date DESC OFFSET 10 LIMIT 10; SELECT * FROM transactions OFFSET 10 ORDER BY transaction_date DESC LIMIT 10;SELECT * FROM transactions ORDER BY transaction_date DESC LIMIT 10 OFFSET 5;

OFFSET can be combined with ORDER BY to skip a specific number of rows before returning the result set. The correct scripts will demonstrate how to use ORDER BY with OFFSET in PostgreSQL.

Q30

Multiple Choice

Identify the SQL scripts that correctly perform an ORDER BY operation with UNION in PostgreSQL.

SELECT * FROM (SELECT * FROM employees UNION SELECT * FROM contractors) AS combined ORDER BY salary ASC; SELECT * FROM employees UNION SELECT * FROM contractors ORDER BY salary ASC; SELECT * FROM employees UNION ALL SELECT * FROM contractors ORDER BY salary DESC;SELECT * FROM (SELECT * FROM employees UNION SELECT * FROM contractors ORDER BY salary ASC) AS combined;

The UNION operator can be used to combine result sets, and when combined with ORDER BY, it can sort the combined data. The correct scripts will demonstrate how to use ORDER BY with UNION in PostgreSQL.

PostgreSQL Database Quiz Questions