15 SQL WHERE Clause Practice Problems with Solutions

Solution

SELECT *
FROM employees
WHERE department = 'Sales';

Explanation

WHERE department = 'Sales' tells the database to only return rows where the department column equals 'Sales' exactly. Every other row is filtered out. Notice the text value is wrapped in single quotes — this is always required for text comparisons in SQL.

Solution

SELECT *
FROM orders
WHERE shipping_method = 'Standard';

Explanation

WHERE shipping_method = 'Standard' filters the results to only rows where the shipping method is Standard. Orders shipped via Express or any other method are excluded. SELECT * returns all columns for the matching rows.

Solution

SELECT *
FROM rental_listings
WHERE property_type = 'Apartment';

Explanation

WHERE property_type = 'Apartment' filters to only Apartment listings. All other property types like House or Studio are excluded. The text value must match exactly — 'apartment' in lowercase would not match if the data stores it as 'Apartment'.

Solution

SELECT first_name, last_name, job_title
FROM employees
WHERE job_title = 'Manager';

Explanation

WHERE job_title = 'Manager' filters to only Manager rows. The SELECT clause then limits which columns are shown — just first_name, last_name, and job_title. Notice you can filter on a column without including it in SELECT, but here job_title is included in both.

Solution

SELECT *
FROM orders
WHERE total_usd > 100;

Explanation

WHERE total_usd > 100 keeps only rows where the order total exceeds $100. Orders worth exactly $100 are excluded because > means strictly greater than. If you wanted to include $100 orders, you'd use >= 100 instead. Notice there are no quotes around the number.

Solution

SELECT *
FROM rental_listings
WHERE price_per_night <= 150;

Explanation

WHERE price_per_night <= 150 keeps rows where the nightly price is $150 or below. The <= operator means "less than or equal to" so listings priced at exactly $150 are included. Listings priced above $150 are filtered out.

Solution

SELECT *
FROM employees
WHERE salary >= 60000;

Explanation

WHERE salary >= 60000 keeps employees earning $60,000 or more. The >= operator means "greater than or equal to" so employees earning exactly $60,000 are included. Employees earning less than $60,000 are excluded.

Solution

SELECT listing_id, city, rating
FROM rental_listings
WHERE rating > 4.5;

Explanation

WHERE rating > 4.5 filters to only highly rated listings. The SELECT clause limits the output to just three columns — listing_id, city, and rating. You can combine selective column choosing with WHERE filtering in the same query.

Solution

SELECT *
FROM employees
WHERE department = 'Sales'
ORDER BY salary DESC;

Explanation

WHERE department = 'Sales' filters to only Sales employees first. ORDER BY salary DESC then sorts those filtered results from highest to lowest salary. The filtering happens before the sorting — SQL always processes WHERE before ORDER BY.

Solution

SELECT *
FROM orders
WHERE total_usd > 50
ORDER BY order_date DESC;

Explanation

WHERE total_usd > 50 filters to orders over $50. ORDER BY order_date DESC then sorts those orders so the most recent appear first. This is a common pattern — filter to relevant rows, then sort them in a useful order.

Solution

SELECT city, price_per_night, rating
FROM rental_listings
WHERE property_type = 'Apartment'
ORDER BY price_per_night;

Explanation

WHERE property_type = 'Apartment' filters to only Apartment listings. ORDER BY price_per_night sorts those results from cheapest to most expensive — no DESC needed since ascending is the default. The SELECT clause limits the output to just the three most relevant columns.

Solution

SELECT *
FROM employees
WHERE department = 'Sales'
AND salary > 50000;

Explanation

AND combines two conditions — both must be true for a row to be included. This query only returns employees who are in Sales AND earn more than $50,000. A Sales employee earning $40,000 would be excluded. An Engineering employee earning $80,000 would also be excluded.

Solution

SELECT *
FROM rental_listings
WHERE city = 'Paris'
OR city = 'Rome';

Explanation

OR means at least one condition must be true. This query returns listings where the city is Paris OR the city is Rome — so listings from either city are included. A listing in London would be excluded since it doesn't match either condition.

Solution

SELECT *
FROM orders
WHERE status = 'Pending'
AND total_usd > 75;

Explanation

Both conditions must be true for a row to be returned. A Pending order worth $60 is excluded because it doesn't meet the price condition. A Delivered order worth $100 is excluded because it doesn't meet the status condition. Only Pending orders over $75 are returned.

Solution

SELECT first_name, last_name, department, salary
FROM employees
WHERE (department = 'Marketing' OR department = 'Finance')
AND salary >= 70000;

Explanation

This query mixes OR and AND. The parentheses around the OR conditions are important — they ensure the department filter is evaluated first as a group, and then the salary condition is applied to that result. Without parentheses, SQL might evaluate the AND before the OR and return unexpected results. When mixing AND and OR, always use parentheses to make your intentions clear.