Aggregate SQL query across multiple tables by grouping - sql

Question

I want to group the record from the multiple tables.
Sample data:
create table UserTable (
Id integer not null,
Name varchar(12) not null
);
insert into UserTable values (1, 'A B');
insert into UserTable values (2, 'A C');
insert into UserTable values (3, 'A C A C');
insert into UserTable values (4, 'A C C');
insert into UserTable values (5, 'A C B');
insert into UserTable values (6, 'A C C');
insert into UserTable values (7, 'A C D');
insert into UserTable values (8, 'A C E');
insert into UserTable values (9, 'A C F');
create table LogTable (
LogId integer not null,
Username varchar(12) not null,
Event varchar(12) not null
);
insert into LogTable values (1, 'A C A C', 'Read');
insert into LogTable values (2, 'A C F', 'Write');
insert into LogTable values (3, 'A C F', 'Read');
insert into LogTable values (4, 'A C C', 'Update');
insert into LogTable values (5,'A C C', 'Read');
insert into LogTable values (6,'A C F', 'Read');
insert into LogTable values (7,'A C F', 'Update');
insert into LogTable values (7,'A C F', 'Write');
insert into LogTable values (7,'A C E','Update');
insert into LogTable values (7,'A C F', 'Delete');
insert into LogTable values (10,'A C B', 'Delete');
insert into LogTable values (11, 'A C F','Copy');
insert into LogTable values (12, 'A C B','Read');
insert into LogTable values (13, 'A C F','Update');
insert into LogTable values (14, 'A C F','Copy');
insert into LogTable values (15, 'A C F','Read');
insert into LogTable values (16, 'A C F','Update');
insert into LogTable values (17, 'A C F','Copy');
insert into LogTable values (18, 'A C C','Read');
insert into LogTable values (19, 'A C D','Update');
create table Activity (
Id integer not null,
ActivityType varchar(12) not null,
UserId varchar(12) not null
);
insert into Activity values (1, 'Videos', 8);
insert into Activity values (2, 'Text', 7);
insert into Activity values (3, 'Page', 7);
insert into Activity values (4, 'Text', 7);
insert into Activity values (5, 'Text', 9);
insert into Activity values (6, 'Chat', 8);
insert into Activity values (7, 'Chat', 5);
insert into Activity values (7, 'File', 8);
insert into Activity values (7, 'Videos', 1);
insert into Activity values (7, 'Text', 4);
insert into Activity values (10, 'Image', 4);
insert into Activity values (11, 'Image', 6);
insert into Activity values (12, 'Chat', 3);
insert into Activity values (13, 'Chat', 2);
insert into Activity values (14, 'Page', 1);
insert into Activity values (15, 'Vidoes',1);
insert into Activity values (16, 'Vidoes',6);
insert into Activity values (17, 'Vidoes',5);
insert into Activity values (18, 'Vidoes',5);
insert into Activity values (19, 'Chat', 5);
What I have tried:
SELECT UT.Id,UT.Name,
SUM(CASE
WHEN LT.Event = 'Read' THEN 1
ELSE 0 END
) AS [USER READ],
SUM(CASE
WHEN LT.Event = 'Delete' THEN 1
ELSE 0 END
) AS [USER DELETE],
SUM(CASE
WHEN AC.ActivityType = 'Videos' THEN 1
WHEN AC.ActivityType = 'Text' THEN 1
WHEN AC.ActivityType = 'Page' THEN 1
WHEN AC.ActivityType = 'Image' THEN 1
ELSE 0 END
) AS [LEARNING ACTIVITY],
SUM(CASE WHEN AC.ActivityType = 'Chat' THEN 1 ELSE 0 END) AS [Chat]
FROM UserTable UT
LEFT JOIN Activity AC ON UT.Id = AC.UserId
LEFT JOIN LogTable LT ON LT.Username = UT.Name
GROUP BY UT.Id, UT.Name
Desired Output:
Id | Name | LEARNING ACTIVITY | Chat | USER READ | USER DELETE|
------------------------------------------------------------------------
1 | A B | 2 | 0 | 0 | 0 |
2 | A C | 0 | 1 | 0 | 0 |
3 | A C A C | 0 | 1 | 1 | 0 |
4 | A C C | 2 | 0 | 2 | 0 |
5 | A C B | 0 | 2 | 1 | 1 |
6 | A C R | 1 | 0 | 0 | 0 |
7 | A C D | 3 | 0 | 0 | 0 |
8 | A C E | 1 | 1 | 0 | 0 |
9 | A C F | 1 | 0 | 3 | 1 |
How can I aggregate two tables which are not related and group by with Id and Name?
Join and Aggregate Activity with Users
Learning Activity is the sum of (Videos, Text, Page and Image) as ActivityType
Chat is all the rows having the Chat as ActivityType
Join and Aggregate LogTable with Users

Answer 1

You should aggregate before joining, this avoids getting a many-to-many-join which results in overcounting:
SELECT UT.Id,UT.Name,
coalesce([LEARNING ACTIVITY],0),
coalesce([Chat],0),
coalesce([USER READ],0),
coalesce([USER DELETE],0)
FROM UserTable UT
LEFT JOIN
(
select UserId,
SUM(CASE
WHEN ActivityType = 'Videos' THEN 1
WHEN ActivityType = 'Text' THEN 1
WHEN ActivityType = 'Page' THEN 1
WHEN ActivityType = 'Image' THEN 1
ELSE 0
END) AS [LEARNING ACTIVITY],
SUM(CASE WHEN ActivityType = 'Chat' THEN 1 ELSE 0 END) AS [Chat]
from Activity
group by UserId
) AC
ON UT.Id = AC.UserId
LEFT JOIN
(
select Username,
SUM(CASE
WHEN Event = 'Read' THEN 1
ELSE 0 END
) AS [USER READ],
SUM(CASE
WHEN Event = 'Delete' THEN 1
ELSE 0 END
) AS [USER DELETE]
from LogTable
group by UserName
) LT
ON LT.Username = UT.Name
See fiddle
Simplifying the CASEs (COALESCE takes care of NULLs):
SELECT UT.Id,UT.Name,
coalesce([LEARNING ACTIVITY],0),
coalesce([Chat],0),
coalesce([USER READ],0),
coalesce([USER DELETE],0)
FROM UserTable UT
LEFT JOIN
(
select UserId,
SUM(CASE WHEN ActivityType IN ('Videos','Text','Page','Image') THEN 1 END) AS [LEARNING ACTIVITY],
SUM(CASE WHEN ActivityType = 'Chat' THEN 1 END) AS [Chat]
from Activity
group by UserId
) AC
ON UT.Id = AC.UserId
LEFT JOIN
(
select Username,
SUM(CASE WHEN Event = 'Read' THEN 1 END) AS [USER READ],
SUM(CASE WHEN Event = 'Delete' THEN 1 END) AS [USER DELETE]
from LogTable
group by UserName
) LT
ON LT.Username = UT.Name

Answer 2

I recommend you make use of windowing functions and outer apply to do the aggregations you need. Here is the query I came up with that matches your expected result:
https://learn.microsoft.com/en-us/sql/t-sql/queries/select-over-clause-transact-sql?view=sql-server-ver15
https://learn.microsoft.com/en-us/u-sql/statements-and-expressions/select/from/select-selecting-from-cross-apply-and-outer-apply
select distinct
UserId,
UT.Name,
sum(case when A.ActivityType in ('Videos','Text','Page','Image') then 1 else 0 end) over (partition by UserId) [Learning Activity],
sum(case when A.ActivityType = 'Chat' then 1 else 0 end) over (partition by UserId) Chat,
coalesce(LT2.[User Read],0) as [User Read],
coalesce(LT2.[User Delete],0) as [User Delete]
from Activity A
join UserTable UT
on A.UserId = UT.Id
outer apply
(
select distinct
sum(case when LT.[Event] = 'Read' then 1 else 0 end) over (partition by UserId) [User Read],
sum(case when LT.[Event] = 'Delete' then 1 else 0 end) over (partition by UserId) [User Delete]
from LogTable LT
where LT.Username = UT.Name
) LT2