CREATE TABLE A (
XYEAR INT, 
Q1 INT,
Q2 INT,
Q3 INT,
Q4 INT);

INSERT INTO A
VALUES
(2017,200,250,235,266),
(2018,195,220,215,240);

SELECT XYEAR,'Q1' AS 'QQ',MAX(Q1) AS 'AMOUNT'
FROM A
GROUP BY XYEAR
UNION 
SELECT XYEAR,'Q2' AS 'QQ',MAX(Q2) AS 'AMOUNT'
FROM A
GROUP BY XYEAR
UNION
SELECT XYEAR,'Q3' AS 'QQ',MAX(Q3) AS 'AMOUNT'
FROM A
GROUP BY XYEAR
UNION
SELECT XYEAR,'Q4' AS 'QQ',MAX(Q4) AS 'AMOUNT'
FROM A
GROUP BY XYEAR
ORDER BY XYEAR,QQ

Demo

使用PostgreSQL

create table it0422 (
  xyear int not null
, q1 int not null
, q2 int not null
, q3 int not null
, q4 int not null
);

insert into it0422 values
(2017,200,250,235,266),
(2018,195,220,215,240);

select xyear as "年度"
     , unnest(array['q1', 'q2', 'q3', 'q4']) as "各季"
     , unnest(array[q1, q2, q3, q4]) as "購買金額"
  from it0422
 order by 1,2;

 年度 | 各季 | 購買金額
------+------+----------
 2017 | q1   |      200
 2017 | q2   |      250
 2017 | q3   |      235
 2017 | q4   |      266
 2018 | q1   |      195
 2018 | q2   |      220
 2018 | q3   |      215
 2018 | q4   |      240
(8 rows)

create table it0422x as
select xyear 
     , unnest(array['q1', 'q2', 'q3', 'q4']) as quarter
     , unnest(array[q1, q2, q3, q4]) as qty
  from it0422
 order by 1,2;

select *
  from it0422x;

 xyear | quarter | qty
-------+---------+-----
  2017 | q1      | 200
  2017 | q2      | 250
  2017 | q3      | 235
  2017 | q4      | 266
  2018 | q1      | 195
  2018 | q2      | 220
  2018 | q3      | 215
  2018 | q4      | 240
(8 rows)

select xyear as year
     , min(qty) filter (where quarter = 'q1') as q1
     , min(qty) filter (where quarter = 'q2') as q2
     , min(qty) filter (where quarter = 'q3') as q3
     , min(qty) filter (where quarter = 'q4') as q4
  from it0422x
 group by xyear
 order by xyear;

 year | q1  | q2  | q3  | q4
------+-----+-----+-----+-----
 2017 | 200 | 250 | 235 | 266
 2018 | 195 | 220 | 215 | 240
(2 rows)

-- 使用補助表的方式 
with t1 (quarter, q1, q2, q3, q4) as (
values ('q1', 1, 0, 0, 0)
     , ('q2', 0, 1, 0, 0)
     , ('q3', 0, 0, 1, 0)
     , ('q4', 0, 0, 0, 1)
)
select x.xyear as year
     , sum(x.qty * t1.q1) as q1
     , sum(x.qty * t1.q2) as q2
     , sum(x.qty * t1.q3) as q3
     , sum(x.qty * t1.q4) as q4
  from it0422x x
     , t1
 where x.quarter = t1.quarter
 group by x.xyear
 order by 1;

 year | q1  | q2  | q3  | q4
------+-----+-----+-----+-----
 2017 | 200 | 250 | 235 | 266
 2018 | 195 | 220 | 215 | 240
(2 rows)

-- 使用 case when 方式

select xyear as year
     , min(case 
             when quarter = 'q1' then qty
             else null
           end) as q1
     , min(case 
             when quarter = 'q2' then qty
             else null
           end) as q2
     , min(case 
             when quarter = 'q3' then qty
             else null
           end) as q3
     , min(case 
             when quarter = 'q4' then qty
             else null
           end) as q4
  from it0422x
 group by xyear
 order by xyear;

 year | q1  | q2  | q3  | q4
------+-----+-----+-----+-----
 2017 | 200 | 250 | 235 | 266
 2018 | 195 | 220 | 215 | 240
(2 rows)

-- 大多數 RDBMS 都有 case when , filter 目前是 PostgreSQL 有
-- 可以觀察到, 使用 filter 語法較為簡潔
-- 不管是 補助表, case when , 還是 filter.其實三種方式的原理都是一樣的.

demo

MS SQL 的話，可以使用 unpivot 來做到

雖然樓上已經有許多解答了，但還是想分享自己練習的結果

--建表
DECLARE @XP AS TABLE
(
   [年度] varchar(4) NOT NULL,
   [Q1] decimal(11),
   [Q2] decimal(11),
   [Q3] decimal(11),
   [Q4] decimal(11)
)

--放入參考資料
INSERT INTO @XP VALUES('2017',200,250,235,266)
INSERT INTO @XP VALUES('2018',195,220,215,240)

SELECT * FROM @XP

SELECT XP.[年度] 年度,a.各季,a.購買金額
FROM @XP XP
LEFT JOIN ( select [年度] 年度,'Q1' 各季,Q1 購買金額 from @XP ) a ON XP.年度 = a.年度
union
SELECT XP.[年度] 年度,a.各季,a.購買金額
FROM @XP XP
LEFT JOIN ( select [年度] 年度,'Q2' 各季,Q2 購買金額 from @XP ) a ON XP.年度 = a.年度
union
SELECT XP.[年度] 年度,a.各季,a.購買金額
FROM @XP XP
LEFT JOIN ( select [年度] 年度,'Q3' 各季,Q3 購買金額 from @XP ) a ON XP.年度 = a.年度
union
SELECT XP.[年度] 年度,a.各季,a.購買金額
FROM @XP XP
LEFT JOIN ( select [年度] 年度,'Q4' 各季,Q4 購買金額 from @XP ) a ON XP.年度 = a.年度