SQL Server 2022

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CREATE TABLE Users (id varchar(20) PRIMARY KEY);

INSERT Users VALUES ('scott'), ('tiger');

CREATE TABLE Content (
  "Month" INTEGER,
  "Id" VARCHAR(20),
  "Sequence" INTEGER,
  "Content" VARCHAR(10)
);

INSERT INTO Content
  ("Month", "Id", "Sequence", "Content")
VALUES
  ('01', 'scott', '1', '01_scott_1'),
  ('01', 'scott', '2', '01_scott_2'),
  ('02', 'scott', '1', '02_scott_1'),
  ('02', 'tiger', '1', '02_tiger_1'),
  ('02', 'tiger', '2', '02_tiger_2'),
  ('03', 'tiger', '1', '03_tiger_1'),
  ('03', 'tiger', '2', '03_tiger_2'),
  ('03', 'tiger', '3', '03_tiger_3');
10 rows affected

SELECT
  u.Id,
  c.*
FROM Users u
OUTER APPLY (
    SELECT
      MAX(CASE WHEN c.Month = '01' THEN c.Content END) AS Month_1_Content,
      MAX(CASE WHEN c.Month = '02' THEN c.Content END) AS Month_2_Content,
      MAX(CASE WHEN c.Month = '03' THEN c.Content END) AS Month_3_Content
    FROM Content c 
    WHERE u.Id = c.Id
    GROUP BY
      c.Sequence
) c;


Id
Month_1_Content
Month_2_Content
Month_3_Content


scott
01_scott_1
02_scott_1
null

scott
01_scott_2
null
null

tiger
null
02_tiger_1
03_tiger_1

tiger
null
02_tiger_2
03_tiger_2

tiger
null
null
03_tiger_3


Warning: Null value is eliminated by an aggregate or other SET operation.


SELECT
  c.*
FROM Users u
LEFT JOIN (
    SELECT
      c.id,
      MAX(CASE WHEN c.Month = '01' THEN c.Content END) AS Month_1_Content,
      MAX(CASE WHEN c.Month = '02' THEN c.Content END) AS Month_2_Content,
      MAX(CASE WHEN c.Month = '03' THEN c.Content END) AS Month_3_Content
    FROM Content c
    GROUP BY
      c.Id,
      c.Sequence
) c ON u.Id = c.Id;


id
Month_1_Content
Month_2_Content
Month_3_Content


scott
01_scott_1
02_scott_1
null

scott
01_scott_2
null
null

tiger
null
02_tiger_1
03_tiger_1

tiger
null
02_tiger_2
03_tiger_2

tiger
null
null
03_tiger_3


Warning: Null value is eliminated by an aggregate or other SET operation.

Id	Month_1_Content	Month_2_Content	Month_3_Content
scott	01_scott_1	02_scott_1	null
scott	01_scott_2	null	null
tiger	null	02_tiger_1	03_tiger_1
tiger	null	02_tiger_2	03_tiger_2
tiger	null	null	03_tiger_3