UPDATE SQL 查询中的聚合

Question

所以，我目前有两个 table，一个包含每个对象的固定部分，另一个包含每个对象的可变数量的属性，作为 key/value 对。我想将这些属性转换为 JSON 映射格式中主 table 中的 CLOB 字段。

create table test_a (id integer, properties clob);
create table test_b (id integer, a_id integer, key char(30), value char(30));

insert into test_a values(1,'');
insert into test_a values(2,'');
insert into test_a values(3,'');

insert into test_b values (1, 1, 'k1', 'v1');
insert into test_b values (2, 1, 'k2', 'v2');
insert into test_b values (3, 2, 'k3', 'v3');
insert into test_b values (4, 2, 'k4', 'v4');
insert into test_b values (5, 2, 'k5', 'v5');
insert into test_b values (6, 2, 'k6', 'v6');

我可以通过以下查询构建我想要的 JSON：

WITH PROPS AS
  (SELECT '"'
    ||trim(KEY)
    ||'":"'
    ||trim(value)
    ||'"' json,
    test_b.*
  FROM test_b
  )
SELECT test_a.id,
  '{'
  ||
  (SELECT listagg(json, ',') within GROUP (
  ORDER BY props.key)
  FROM PROPS
  WHERE PROPS.A_ID = test_a.id
  )
  || '}'
FROM TEST_A
INNER JOIN PROPS
ON TEST_A.ID = PROPS.A_ID
GROUP BY TEST_A.ID ;

我得到了想要的结果

1   "{""k1"":""v1"",""k2"":""v2""}"
2   "{""k3"":""v3"",""k4"":""v4"",""k5"":""v5"",""k6"":""v6""}"

但是当我尝试使用这个结果插入到master中时table，我得到了错误

UPDATE TEST_A SET PROPERTIES = (
WITH PROPS AS
  (SELECT '"'
    ||trim(key)
    ||'":"'
    ||trim(value)
    ||'"' json,
    test_b.*
  FROM test_b
  )
SELECT '{'
  ||
  (SELECT listagg(json, ',') within GROUP (order by props.key) FROM PROPS
  WHERE PROPS.A_ID = test_a.id)
  || '}'  from TEST_A INNER JOIN PROPS ON TEST_A.ID = PROPS.A_ID GROUP BY TEST_A.ID
) ;

Error report -
SQL Error: ORA-01427: single-row subquery returns more than one row
01427. 00000 -  "single-row subquery returns more than one row"

有什么想法吗？

Answer 1

您需要一个相关的子查询而不是 group by。整个外部查询看起来不对，所以我认为您需要这样的东西：

UPDATE TEST_A
    SET PROPERTIES = (
        WITH PROPS AS (
              SELECT '"'||trim(key)||'":"'||trim(value)||'"' as json,
                     test_b.*
              FROM test_b
             )
        SELECT '{' || listagg(json, ',') within GROUP (order by props.key) || '}'
        FROM PROPS
        WHERE PROPS.A_ID = test_a.id
       ) ;

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