EasySQL challenge #87WHERE

Users With Phone

Find users who have a phone number.

The challenge runs on the SQLabHub practice database (SQLite) and uses the users table. You can solve it in the browser, with nothing to install.

Solve This SQL Challenge

The task

Find users who have a phone number.

A correct answer returns 150 rows with 10 columns: id, first_name, last_name, email, phone, city, country, created_at, status, is_premium.

Tables used in this challenge

`users` 150 rows

id INTEGER (PK) · first_name TEXT · last_name TEXT · email TEXT · phone TEXT · city TEXT · country TEXT · created_at TEXT · status TEXT · is_premium INTEGER

First 3 rows of the users table
id	first_name	last_name	email	phone	city	country	created_at	status
1	Jennifer	Torres	jennifer.torres57@icloud.com	+1-263-376-2371	Houston	Canada	2024-04-13	active
2	Donna	Adams	donna.adams52@gmail.com	+1-753-780-6670	Fort Worth	Canada	2020-09-15	inactive
3	Kenneth	Young	kenneth.young94@proton.me	+1-440-743-9503	Austin	USA	2023-09-05	active

The first rows of each table are shown. See how all the tables relate on the database schema page.

Expected output

Expected output of the challenge
id	first_name	last_name	email	phone	city	country	created_at	status	is_premium
1	Jennifer	Torres	jennifer.torres57@icloud.com	+1-263-376-2371	Houston	Canada	2024-04-13	active	0
2	Donna	Adams	donna.adams52@gmail.com	+1-753-780-6670	Fort Worth	Canada	2020-09-15	inactive	0
3	Kenneth	Young	kenneth.young94@proton.me	+1-440-743-9503	Austin	USA	2023-09-05	active	0
4	Michael	Carter	michael.carter46@yahoo.com	+1-967-275-1964	San Antonio	France	2024-12-19	active	1
5	Robert	Campbell	robert.campbell92@icloud.com	+1-549-212-8814	New York	USA	2019-09-23	active	1

First 5 of 150 rows. This is the output of the model solution on the practice database. The task does not fix a sort order, so your rows may come back in a different order.

What you practise

Returning every column of a table with SELECT *
Filtering rows with a WHERE condition
Testing for missing values with IS NULL and IS NOT NULL

Hint and approach

Try the challenge first. Open these only when you need them.

Show the hint

IS NOT NULL

Show the step-by-step approach

How the model solution is built, in the order the database evaluates it:

Read from the users table.
Filter in WHERE: keep the rows where phone has a value (it is not NULL).
Return every column with SELECT *.

Model solution

Checking your session…

What to watch for

IS NULL. Comparing with = NULL or <> NULL never matches any row. NULL has to be tested with IS NULL or IS NOT NULL.
WHERE. WHERE is evaluated before the SELECT list, so it cannot use a column alias defined there or the result of an aggregate.
SELECT *. SELECT * is fine for exploring, but its output changes whenever a column is added to the table. Queries that feed a report should name their columns.