CODEWITHSUNDEEP
sqljsonoracle-databaseoracle12c
Luca_brasi
Luca_brasi

Reputation: 89

How can I select a nested json object with a group by clause in oracle sql from a table?

Let's say I have the following statement:

WITH t AS
(
  SELECT 'A' AS level_0, 'A1' AS level_1_1, 'object_1' AS level_1_2, 'A11' AS level_2_1, 'B11' AS level_2_2 FROM dual
  UNION ALL
  SELECT 'A' AS level_0, 'A1' AS level_1_1, 'object_1' AS level_1_2, 'A12' AS level_2_1, 'B12' AS level_2_2 FROM dual
  UNION ALL
  SELECT 'A' AS level_0, 'A1' AS level_1_1, 'object_1' AS level_1_2, 'A13' AS level_2_1, 'B13' AS level_2_2 FROM dual
  UNION ALL
  SELECT 'A' AS level_0, 'A1' AS level_1_1, 'object_1' AS level_1_2, 'A14' AS level_2_1, 'B14' AS level_2_2 FROM dual
  UNION ALL
  SELECT 'B' AS level_0, 'A1' AS level_1_1, 'object_2' AS level_1_2, 'A11' AS level_2_1, 'B15' AS level_2_2 FROM dual
  UNION ALL
  SELECT 'B' AS level_0, 'A1' AS level_1_1, 'object_2' AS level_1_2, 'A12' AS level_2_1, 'B16' AS level_2_2 FROM dual
  UNION ALL
  SELECT 'B' AS level_0, 'A1' AS level_1_1, 'object_2' AS level_1_2, 'A13' AS level_2_1, 'B17' AS level_2_2 FROM dual
)
SELECT * FROM t

My desired output looks like this:


+---------+---------------------------------------------------------------------------------+
| Level 0 |                                      JSON                                       |
+---------+---------------------------------------------------------------------------------+
| A       | {"level_1_1":"A1","object_1":{"A11":"B11","A12":"B12","A13":"B13","A14":"B14"}} |
| B       | {"level_1_1":"A1","object_2":{"A11":"B15","A12":"B16","A13":"B17"}}             |
+---------+---------------------------------------------------------------------------------+

How do I get this output with a select statement?

Thank you very much for your help!

Upvotes: 4

Views: 3478

Answers (2)

Popeye
Popeye

Reputation: 35900

You can use the GROUP BY, LISTAGG and concatenation as follows:

SQL> with t as(
  2  select 'A' as level_0, 'A1' as level_1_1, 'object_1' as level_1_2, 'A11' as level_2_1, 'B11' as level_2_2 from dual union all
  3  select 'A' as level_0, 'A1' as level_1_1, 'object_1' as level_1_2, 'A12' as level_2_1, 'B12' as level_2_2  from dual union all
  4  select 'A' as level_0, 'A1' as level_1_1, 'object_1' as level_1_2, 'A13' as level_2_1, 'B13' as level_2_2  from dual union all
  5  select 'A' as level_0, 'A1' as level_1_1, 'object_1' as level_1_2, 'A14' as level_2_1, 'B14' as level_2_2  from dual union all
  6  select 'B' as level_0, 'A1' as level_1_1, 'object_2' as level_1_2, 'A11' as level_2_1, 'B15' as level_2_2  from dual union all
  7  select 'B' as level_0, 'A1' as level_1_1, 'object_2' as level_1_2, 'A12' as level_2_1, 'B16' as level_2_2  from dual union all
  8  select 'B' as level_0, 'A1' as level_1_1, 'object_2' as level_1_2, 'A13' as level_2_1, 'B17' as level_2_2  from dual
  9  )
 10  select LEVEL_0,
 11     '{"level_1_1":"'|| level_1_1 || '","'||level_1_2 ||'":{'
 12     || LISTAGG('"' || level_2_1 || '":"' || level_2_2 || '"', ',')
 13  WITHIN GROUP (ORDER BY level_2_1, level_2_2)
 14     || '}}' AS JSON
 15  from  t
 16  GROUP BY LEVEL_0, level_1_1, level_1_2;

LEVEL_0    JSON
---------- -------------------------------------------------------------------------------
A          {"level_1_1":"A1","object_1":{"A11":"B11","A12":"B12","A13":"B13","A14":"B14"}}
B          {"level_1_1":"A1","object_2":{"A11":"B15","A12":"B16","A13":"B17"}}

SQL>

Upvotes: 1

Barbaros Özhan
Barbaros Özhan

Reputation: 65218

JSON_OBJECT() and JSON_OBJECTAGG() functions might be used with proper grouping such as

SELECT level_0,
       JSON_OBJECT(
                   'level_1_1' VALUE level_1_1,
                    level_1_2  VALUE JSON_OBJECTAGG(level_2_1 VALUE level_2_2)
        )
    AS "Result JSON"                           
  FROM t
 GROUP BY level_1_2, level_1_1, level_0

Demo

Upvotes: 3

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