Interview Guides

First and Last User Events | Dataford Interview Questions - Dataford - Ace your Interview

First and Last User Events

Medium

SQL & Data Manipulation

Asked at 2 companies2Window FunctionsRankingDate Functions

Also asked at

Problem

Task

StreamWave tracks user activity across web and mobile sessions. Write a PostgreSQL query to return each active user's first and last event based on event timestamp.

Requirements

Include only users whose status is 'active'.
Return one row per active user, even if the user has no events.
For each user, show the first event type and timestamp, and the last event type and timestamp.
If multiple events share the same timestamp for a user, break ties using the smaller event_id for the first event and the larger event_id for the last event.
Order the final result by user_id.

Table Definitions

`users`

column	type	description
user_id	INT	Primary key for the user
full_name	VARCHAR(100)	User name
status	VARCHAR(20)	Account status
signup_date	DATE	Date the user signed up

`platforms`

column	type	description
platform_id	INT	Primary key for platform
platform_name	VARCHAR(50)	Platform name

`events`

column	type	description
event_id	INT	Primary key for event
user_id	INT	User who generated the event
platform_id	INT	Platform where the event occurred
event_type	VARCHAR(50)	Event name
event_time	TIMESTAMP	Event timestamp

Sample Data

Representative rows are included below in the dataset. Some users have no events, some events have NULL platforms, and some users have multiple events at the same timestamp.

Expected Output

user_id	full_name	first_event_type	first_event_time	last_event_type	last_event_time
1	Ava Chen	login	2024-02-01 09:00:00	purchase	2024-02-03 18:30:00
2	Ben Ortiz	login	2024-02-01 08:00:00	logout	2024-02-01 08:00:00
4	Diego Park	NULL	NULL	NULL	NULL
5	Ella Singh	login	2024-02-10 07:45:00	support_ticket	2024-02-11 16:00:00
7	Grace Kim	login	2024-02-15 12:00:00	login	2024-02-15 12:00:00

Schema

users

Column	Type	Description
user_idPK	INT	Primary key for the user
full_name	VARCHAR(100)	User full name
status	VARCHAR(20)	Account status such as active, inactive, or banned
signup_date	DATE	Date the user signed up

platforms

Column	Type	Description
platform_idPK	INT	Primary key for the platform
platform_name	VARCHAR(50)	Platform name such as web or ios

events

Column	Type	Description
event_idPK	INT	Primary key for the event
user_id	INT	User who generated the event
platform_id	INT	Platform where the event occurred
event_type	VARCHAR(50)	Type of event
event_time	TIMESTAMP	Timestamp when the event occurred

users

user_id	full_name	status	signup_date
5	Ella Singh	active	2024-02-01
2	Ben Ortiz	active	2024-01-20
6	Farah Ali	inactive	2024-02-05
1	Ava Chen	active	2024-01-15
4	Diego Park	active
3	Cara Lopez	banned	2024-01-25
7	Grace Kim	active	2024-02-12
8	Hugo Reed	inactive	2024-02-14
1	Ella Singh	active	2024-02-14
2	Cara Lopez	active	2024-02-16
3	Grace Kim	inactive	2024-01-18
4	Hugo Reed	active	2024-01-14
5	Ben Ortiz	active	2024-02-15
6	Ella Singh	inactive	2024-01-21
7	Farah Ali	active	2024-02-02
8	Cara Lopez	active	2024-02-14
9	Hugo Reed	inactive	2024-01-19
10	Hugo Reed	banned	2024-02-15
11	Cara Lopez	inactive	2024-01-14
12	Ben Ortiz	active	2024-01-15
13	Ben Ortiz	inactive	2024-01-31
14	Ava Chen	active	2024-02-03
15	Cara Lopez	active	2024-01-17
16	Ava Chen	inactive	2024-01-25
17	Diego Park	active	2024-02-09
18	Diego Park	inactive	2024-01-25

events

event_id	user_id	platform_id	event_type	event_time
108	5	2	support_ticket	2024-02-11 16:00:00
102	1	2	view_item	2024-02-01 09:05:00
111	6	1	login	2024-02-12 08:00:00
101	1	1	login	2024-02-01 09:00:00
106	2	1	logout	2024-02-01 08:00:00
110	3	3	login	2024-02-05 10:00:00
104	1		purchase	2024-02-03 18:30:00
109	5	99	logout	2024-02-11 16:00:00
103	1	2	add_to_cart	2024-02-03 18:30:00
112	7	1	login	2024-02-15 12:00:00
105	2	1	login	2024-02-01 08:00:00
107	5	1	login	2024-02-10 07:45:00
1	99	95	login	2024-02-05 07:34:48
2	95	81	login	2024-02-11 11:07:03
3	23	27	login	2024-02-14 06:45:51
4	64	64	logout	2024-02-04 23:06:00
5	95	36	add_to_cart	2024-01-31 04:52:08
6	65	54	purchase	2024-02-06 01:48:27
7	21	45	login	2024-02-03 07:57:56
8	55	25	login	2024-02-13 10:11:06
9	32	15	login	2024-02-16 18:43:34
10	10	24	login	2024-02-17 21:56:45
11	41	35	login	2024-02-08 02:10:07
12	10	9	login	2024-02-02 04:55:57
13	17	8	logout	2024-02-10 13:43:41
14	27	12	support_ticket	2024-02-08 11:37:21
15	59	5	add_to_cart	2024-01-30 16:35:06
16	56	50	support_ticket	2024-02-05 18:38:01

platforms

platform_id	platform_name
3	android
1	web
4	tv
2	ios
5	kiosk
6	voice
7	email
8	partner_api
1	voice
2	email
3	android
4	ios
5	web
6	android
7	partner_api
8	tv
9	android
10	partner_api
11	email
12	voice
13	voice
14	ios
15	kiosk
16	email
17	ios
18	kiosk
19	android
20	web

Expected Output

user_id	full_name	first_event_type	first_event_time	last_event_type	last_event_time
1	Ava Chen	login	2024-02-01 09:00:00	purchase	2024-02-03 18:30:00
2	Ben Ortiz	login	2024-02-01 08:00:00	logout	2024-02-01 08:00:00
4	Diego Park	null	null	null	null
5	Ella Singh	login	2024-02-10 07:45:00	logout	2024-02-11 16:00:00
7	Grace Kim	login	2024-02-15 12:00:00	login	2024-02-15 12:00:00
12	Ben Ortiz	null	null	null	null
14	Ava Chen	null	null	null	null
15	Cara Lopez	null	null	null	null
17	Diego Park	logout	2024-02-10 13:43:41	logout	2024-02-10 13:43:41

Problem

Task

StreamWave tracks user activity across web and mobile sessions. Write a PostgreSQL query to return each active user's first and last event based on event timestamp.

Requirements

Include only users whose status is 'active'.
Return one row per active user, even if the user has no events.
For each user, show the first event type and timestamp, and the last event type and timestamp.
If multiple events share the same timestamp for a user, break ties using the smaller event_id for the first event and the larger event_id for the last event.
Order the final result by user_id.

Table Definitions

`users`

column	type	description
user_id	INT	Primary key for the user
full_name	VARCHAR(100)	User name
status	VARCHAR(20)	Account status
signup_date	DATE	Date the user signed up

`platforms`

column	type	description
platform_id	INT	Primary key for platform
platform_name	VARCHAR(50)	Platform name

`events`

column	type	description
event_id	INT	Primary key for event
user_id	INT	User who generated the event
platform_id	INT	Platform where the event occurred
event_type	VARCHAR(50)	Event name
event_time	TIMESTAMP	Event timestamp

Sample Data

Representative rows are included below in the dataset. Some users have no events, some events have NULL platforms, and some users have multiple events at the same timestamp.

Expected Output

user_id	full_name	first_event_type	first_event_time	last_event_type	last_event_time
1	Ava Chen	login	2024-02-01 09:00:00	purchase	2024-02-03 18:30:00
2	Ben Ortiz	login	2024-02-01 08:00:00	logout	2024-02-01 08:00:00
4	Diego Park	NULL	NULL	NULL	NULL
5	Ella Singh	login	2024-02-10 07:45:00	support_ticket	2024-02-11 16:00:00
7	Grace Kim	login	2024-02-15 12:00:00	login	2024-02-15 12:00:00

Schema

users

Column	Type	Description
user_idPK	INT	Primary key for the user
full_name	VARCHAR(100)	User full name
status	VARCHAR(20)	Account status such as active, inactive, or banned
signup_date	DATE	Date the user signed up

platforms

Column	Type	Description
platform_idPK	INT	Primary key for the platform
platform_name	VARCHAR(50)	Platform name such as web or ios

events

Column	Type	Description
event_idPK	INT	Primary key for the event
user_id	INT	User who generated the event
platform_id	INT	Platform where the event occurred
event_type	VARCHAR(50)	Type of event
event_time	TIMESTAMP	Timestamp when the event occurred

users

user_id	full_name	status	signup_date
5	Ella Singh	active	2024-02-01
2	Ben Ortiz	active	2024-01-20
6	Farah Ali	inactive	2024-02-05
1	Ava Chen	active	2024-01-15
4	Diego Park	active
3	Cara Lopez	banned	2024-01-25
7	Grace Kim	active	2024-02-12
8	Hugo Reed	inactive	2024-02-14
1	Ella Singh	active	2024-02-14
2	Cara Lopez	active	2024-02-16
3	Grace Kim	inactive	2024-01-18
4	Hugo Reed	active	2024-01-14
5	Ben Ortiz	active	2024-02-15
6	Ella Singh	inactive	2024-01-21
7	Farah Ali	active	2024-02-02
8	Cara Lopez	active	2024-02-14
9	Hugo Reed	inactive	2024-01-19
10	Hugo Reed	banned	2024-02-15
11	Cara Lopez	inactive	2024-01-14
12	Ben Ortiz	active	2024-01-15
13	Ben Ortiz	inactive	2024-01-31
14	Ava Chen	active	2024-02-03
15	Cara Lopez	active	2024-01-17
16	Ava Chen	inactive	2024-01-25
17	Diego Park	active	2024-02-09
18	Diego Park	inactive	2024-01-25

events

event_id	user_id	platform_id	event_type	event_time
108	5	2	support_ticket	2024-02-11 16:00:00
102	1	2	view_item	2024-02-01 09:05:00
111	6	1	login	2024-02-12 08:00:00
101	1	1	login	2024-02-01 09:00:00
106	2	1	logout	2024-02-01 08:00:00
110	3	3	login	2024-02-05 10:00:00
104	1		purchase	2024-02-03 18:30:00
109	5	99	logout	2024-02-11 16:00:00
103	1	2	add_to_cart	2024-02-03 18:30:00
112	7	1	login	2024-02-15 12:00:00
105	2	1	login	2024-02-01 08:00:00
107	5	1	login	2024-02-10 07:45:00
1	99	95	login	2024-02-05 07:34:48
2	95	81	login	2024-02-11 11:07:03
3	23	27	login	2024-02-14 06:45:51
4	64	64	logout	2024-02-04 23:06:00
5	95	36	add_to_cart	2024-01-31 04:52:08
6	65	54	purchase	2024-02-06 01:48:27
7	21	45	login	2024-02-03 07:57:56
8	55	25	login	2024-02-13 10:11:06
9	32	15	login	2024-02-16 18:43:34
10	10	24	login	2024-02-17 21:56:45
11	41	35	login	2024-02-08 02:10:07
12	10	9	login	2024-02-02 04:55:57
13	17	8	logout	2024-02-10 13:43:41
14	27	12	support_ticket	2024-02-08 11:37:21
15	59	5	add_to_cart	2024-01-30 16:35:06
16	56	50	support_ticket	2024-02-05 18:38:01

platforms

platform_id	platform_name
3	android
1	web
4	tv
2	ios
5	kiosk
6	voice
7	email
8	partner_api
1	voice
2	email
3	android
4	ios
5	web
6	android
7	partner_api
8	tv
9	android
10	partner_api
11	email
12	voice
13	voice
14	ios
15	kiosk
16	email
17	ios
18	kiosk
19	android
20	web

Expected Output

user_id	full_name	first_event_type	first_event_time	last_event_type	last_event_time
1	Ava Chen	login	2024-02-01 09:00:00	purchase	2024-02-03 18:30:00
2	Ben Ortiz	login	2024-02-01 08:00:00	logout	2024-02-01 08:00:00
4	Diego Park	null	null	null	null
5	Ella Singh	login	2024-02-10 07:45:00	logout	2024-02-11 16:00:00
7	Grace Kim	login	2024-02-15 12:00:00	login	2024-02-15 12:00:00
12	Ben Ortiz	null	null	null	null
14	Ava Chen	null	null	null	null
15	Cara Lopez	null	null	null	null
17	Diego Park	logout	2024-02-10 13:43:41	logout	2024-02-10 13:43:41

Practice SQL

PostgreSQL

Open on desktop for the full SQL editor with syntax highlighting and autocomplete.

Up next

ATop Active Users by Event CountMedium

Classify Power Users by ActivityMedium

7-Day Rolling Active UsersMedium

Next question

First and Last User Events

Medium

SQL & Data Manipulation

Asked at 2 companies2Window FunctionsRankingDate Functions

Also asked at

Problem

Task

StreamWave tracks user activity across web and mobile sessions. Write a PostgreSQL query to return each active user's first and last event based on event timestamp.

Requirements

Include only users whose status is 'active'.
Return one row per active user, even if the user has no events.
For each user, show the first event type and timestamp, and the last event type and timestamp.
If multiple events share the same timestamp for a user, break ties using the smaller event_id for the first event and the larger event_id for the last event.
Order the final result by user_id.

Table Definitions

`users`

column	type	description
user_id	INT	Primary key for the user
full_name	VARCHAR(100)	User name
status	VARCHAR(20)	Account status
signup_date	DATE	Date the user signed up

`platforms`

column	type	description
platform_id	INT	Primary key for platform
platform_name	VARCHAR(50)	Platform name

`events`

column	type	description
event_id	INT	Primary key for event
user_id	INT	User who generated the event
platform_id	INT	Platform where the event occurred
event_type	VARCHAR(50)	Event name
event_time	TIMESTAMP	Event timestamp

Sample Data

Representative rows are included below in the dataset. Some users have no events, some events have NULL platforms, and some users have multiple events at the same timestamp.

Expected Output

user_id	full_name	first_event_type	first_event_time	last_event_type	last_event_time
1	Ava Chen	login	2024-02-01 09:00:00	purchase	2024-02-03 18:30:00
2	Ben Ortiz	login	2024-02-01 08:00:00	logout	2024-02-01 08:00:00
4	Diego Park	NULL	NULL	NULL	NULL
5	Ella Singh	login	2024-02-10 07:45:00	support_ticket	2024-02-11 16:00:00
7	Grace Kim	login	2024-02-15 12:00:00	login	2024-02-15 12:00:00

Schema

users

Column	Type	Description
user_idPK	INT	Primary key for the user
full_name	VARCHAR(100)	User full name
status	VARCHAR(20)	Account status such as active, inactive, or banned
signup_date	DATE	Date the user signed up

platforms

Column	Type	Description
platform_idPK	INT	Primary key for the platform
platform_name	VARCHAR(50)	Platform name such as web or ios

events

Column	Type	Description
event_idPK	INT	Primary key for the event
user_id	INT	User who generated the event
platform_id	INT	Platform where the event occurred
event_type	VARCHAR(50)	Type of event
event_time	TIMESTAMP	Timestamp when the event occurred

users

user_id	full_name	status	signup_date
5	Ella Singh	active	2024-02-01
2	Ben Ortiz	active	2024-01-20
6	Farah Ali	inactive	2024-02-05
1	Ava Chen	active	2024-01-15
4	Diego Park	active
3	Cara Lopez	banned	2024-01-25
7	Grace Kim	active	2024-02-12
8	Hugo Reed	inactive	2024-02-14
1	Ella Singh	active	2024-02-14
2	Cara Lopez	active	2024-02-16
3	Grace Kim	inactive	2024-01-18
4	Hugo Reed	active	2024-01-14
5	Ben Ortiz	active	2024-02-15
6	Ella Singh	inactive	2024-01-21
7	Farah Ali	active	2024-02-02
8	Cara Lopez	active	2024-02-14
9	Hugo Reed	inactive	2024-01-19
10	Hugo Reed	banned	2024-02-15
11	Cara Lopez	inactive	2024-01-14
12	Ben Ortiz	active	2024-01-15
13	Ben Ortiz	inactive	2024-01-31
14	Ava Chen	active	2024-02-03
15	Cara Lopez	active	2024-01-17
16	Ava Chen	inactive	2024-01-25
17	Diego Park	active	2024-02-09
18	Diego Park	inactive	2024-01-25

events

event_id	user_id	platform_id	event_type	event_time
108	5	2	support_ticket	2024-02-11 16:00:00
102	1	2	view_item	2024-02-01 09:05:00
111	6	1	login	2024-02-12 08:00:00
101	1	1	login	2024-02-01 09:00:00
106	2	1	logout	2024-02-01 08:00:00
110	3	3	login	2024-02-05 10:00:00
104	1		purchase	2024-02-03 18:30:00
109	5	99	logout	2024-02-11 16:00:00
103	1	2	add_to_cart	2024-02-03 18:30:00
112	7	1	login	2024-02-15 12:00:00
105	2	1	login	2024-02-01 08:00:00
107	5	1	login	2024-02-10 07:45:00
1	99	95	login	2024-02-05 07:34:48
2	95	81	login	2024-02-11 11:07:03
3	23	27	login	2024-02-14 06:45:51
4	64	64	logout	2024-02-04 23:06:00
5	95	36	add_to_cart	2024-01-31 04:52:08
6	65	54	purchase	2024-02-06 01:48:27
7	21	45	login	2024-02-03 07:57:56
8	55	25	login	2024-02-13 10:11:06
9	32	15	login	2024-02-16 18:43:34
10	10	24	login	2024-02-17 21:56:45
11	41	35	login	2024-02-08 02:10:07
12	10	9	login	2024-02-02 04:55:57
13	17	8	logout	2024-02-10 13:43:41
14	27	12	support_ticket	2024-02-08 11:37:21
15	59	5	add_to_cart	2024-01-30 16:35:06
16	56	50	support_ticket	2024-02-05 18:38:01

platforms

platform_id	platform_name
3	android
1	web
4	tv
2	ios
5	kiosk
6	voice
7	email
8	partner_api
1	voice
2	email
3	android
4	ios
5	web
6	android
7	partner_api
8	tv
9	android
10	partner_api
11	email
12	voice
13	voice
14	ios
15	kiosk
16	email
17	ios
18	kiosk
19	android
20	web

Expected Output

user_id	full_name	first_event_type	first_event_time	last_event_type	last_event_time
1	Ava Chen	login	2024-02-01 09:00:00	purchase	2024-02-03 18:30:00
2	Ben Ortiz	login	2024-02-01 08:00:00	logout	2024-02-01 08:00:00
4	Diego Park	null	null	null	null
5	Ella Singh	login	2024-02-10 07:45:00	logout	2024-02-11 16:00:00
7	Grace Kim	login	2024-02-15 12:00:00	login	2024-02-15 12:00:00
12	Ben Ortiz	null	null	null	null
14	Ava Chen	null	null	null	null
15	Cara Lopez	null	null	null	null
17	Diego Park	logout	2024-02-10 13:43:41	logout	2024-02-10 13:43:41

Problem

Task

StreamWave tracks user activity across web and mobile sessions. Write a PostgreSQL query to return each active user's first and last event based on event timestamp.

Requirements

Include only users whose status is 'active'.
Return one row per active user, even if the user has no events.
For each user, show the first event type and timestamp, and the last event type and timestamp.
If multiple events share the same timestamp for a user, break ties using the smaller event_id for the first event and the larger event_id for the last event.
Order the final result by user_id.

Table Definitions

`users`

column	type	description
user_id	INT	Primary key for the user
full_name	VARCHAR(100)	User name
status	VARCHAR(20)	Account status
signup_date	DATE	Date the user signed up

`platforms`

column	type	description
platform_id	INT	Primary key for platform
platform_name	VARCHAR(50)	Platform name

`events`

column	type	description
event_id	INT	Primary key for event
user_id	INT	User who generated the event
platform_id	INT	Platform where the event occurred
event_type	VARCHAR(50)	Event name
event_time	TIMESTAMP	Event timestamp

Sample Data

Representative rows are included below in the dataset. Some users have no events, some events have NULL platforms, and some users have multiple events at the same timestamp.

Expected Output

user_id	full_name	first_event_type	first_event_time	last_event_type	last_event_time
1	Ava Chen	login	2024-02-01 09:00:00	purchase	2024-02-03 18:30:00
2	Ben Ortiz	login	2024-02-01 08:00:00	logout	2024-02-01 08:00:00
4	Diego Park	NULL	NULL	NULL	NULL
5	Ella Singh	login	2024-02-10 07:45:00	support_ticket	2024-02-11 16:00:00
7	Grace Kim	login	2024-02-15 12:00:00	login	2024-02-15 12:00:00

Schema

users

Column	Type	Description
user_idPK	INT	Primary key for the user
full_name	VARCHAR(100)	User full name
status	VARCHAR(20)	Account status such as active, inactive, or banned
signup_date	DATE	Date the user signed up

platforms

Column	Type	Description
platform_idPK	INT	Primary key for the platform
platform_name	VARCHAR(50)	Platform name such as web or ios

events

Column	Type	Description
event_idPK	INT	Primary key for the event
user_id	INT	User who generated the event
platform_id	INT	Platform where the event occurred
event_type	VARCHAR(50)	Type of event
event_time	TIMESTAMP	Timestamp when the event occurred

users

user_id	full_name	status	signup_date
5	Ella Singh	active	2024-02-01
2	Ben Ortiz	active	2024-01-20
6	Farah Ali	inactive	2024-02-05
1	Ava Chen	active	2024-01-15
4	Diego Park	active
3	Cara Lopez	banned	2024-01-25
7	Grace Kim	active	2024-02-12
8	Hugo Reed	inactive	2024-02-14
1	Ella Singh	active	2024-02-14
2	Cara Lopez	active	2024-02-16
3	Grace Kim	inactive	2024-01-18
4	Hugo Reed	active	2024-01-14
5	Ben Ortiz	active	2024-02-15
6	Ella Singh	inactive	2024-01-21
7	Farah Ali	active	2024-02-02
8	Cara Lopez	active	2024-02-14
9	Hugo Reed	inactive	2024-01-19
10	Hugo Reed	banned	2024-02-15
11	Cara Lopez	inactive	2024-01-14
12	Ben Ortiz	active	2024-01-15
13	Ben Ortiz	inactive	2024-01-31
14	Ava Chen	active	2024-02-03
15	Cara Lopez	active	2024-01-17
16	Ava Chen	inactive	2024-01-25
17	Diego Park	active	2024-02-09
18	Diego Park	inactive	2024-01-25

events

event_id	user_id	platform_id	event_type	event_time
108	5	2	support_ticket	2024-02-11 16:00:00
102	1	2	view_item	2024-02-01 09:05:00
111	6	1	login	2024-02-12 08:00:00
101	1	1	login	2024-02-01 09:00:00
106	2	1	logout	2024-02-01 08:00:00
110	3	3	login	2024-02-05 10:00:00
104	1		purchase	2024-02-03 18:30:00
109	5	99	logout	2024-02-11 16:00:00
103	1	2	add_to_cart	2024-02-03 18:30:00
112	7	1	login	2024-02-15 12:00:00
105	2	1	login	2024-02-01 08:00:00
107	5	1	login	2024-02-10 07:45:00
1	99	95	login	2024-02-05 07:34:48
2	95	81	login	2024-02-11 11:07:03
3	23	27	login	2024-02-14 06:45:51
4	64	64	logout	2024-02-04 23:06:00
5	95	36	add_to_cart	2024-01-31 04:52:08
6	65	54	purchase	2024-02-06 01:48:27
7	21	45	login	2024-02-03 07:57:56
8	55	25	login	2024-02-13 10:11:06
9	32	15	login	2024-02-16 18:43:34
10	10	24	login	2024-02-17 21:56:45
11	41	35	login	2024-02-08 02:10:07
12	10	9	login	2024-02-02 04:55:57
13	17	8	logout	2024-02-10 13:43:41
14	27	12	support_ticket	2024-02-08 11:37:21
15	59	5	add_to_cart	2024-01-30 16:35:06
16	56	50	support_ticket	2024-02-05 18:38:01

platforms

platform_id	platform_name
3	android
1	web
4	tv
2	ios
5	kiosk
6	voice
7	email
8	partner_api
1	voice
2	email
3	android
4	ios
5	web
6	android
7	partner_api
8	tv
9	android
10	partner_api
11	email
12	voice
13	voice
14	ios
15	kiosk
16	email
17	ios
18	kiosk
19	android
20	web

Expected Output

user_id	full_name	first_event_type	first_event_time	last_event_type	last_event_time
1	Ava Chen	login	2024-02-01 09:00:00	purchase	2024-02-03 18:30:00
2	Ben Ortiz	login	2024-02-01 08:00:00	logout	2024-02-01 08:00:00
4	Diego Park	null	null	null	null
5	Ella Singh	login	2024-02-10 07:45:00	logout	2024-02-11 16:00:00
7	Grace Kim	login	2024-02-15 12:00:00	login	2024-02-15 12:00:00
12	Ben Ortiz	null	null	null	null
14	Ava Chen	null	null	null	null
15	Cara Lopez	null	null	null	null
17	Diego Park	logout	2024-02-10 13:43:41	logout	2024-02-10 13:43:41

Practice SQL

PostgreSQL

Open on desktop for the full SQL editor with syntax highlighting and autocomplete.

Up next

ATop Active Users by Event CountMedium

Classify Power Users by ActivityMedium

7-Day Rolling Active UsersMedium

Next question