DB2 Avoid Duplicates in JSON_ARRAY - db2

Question

I am using DB2LUW 11.5.
I build a json and gets an output like this
{
"ID": 1,
"NAME": "a",
"B_OBJECTS": [{
"ID": 1,
"SIZE": 10
}, {
"ID": 1,
"SIZE": 20
}
]
}
But I want the id from B_OBJECTS listed only once.
{
"ID": 1,
"NAME": "a",
"B_OBJECTS": [{
"ID": 1,
"SIZE": 10
}
]
}
Here is my query...
WITH TABLE_A(ID,NAME) AS (
VALUES (1, 'a')),
TABLE_B(ID, ID_A, SIZE) AS (
VALUES (1, 1, 10), (1, 1, 20)),
JSON_STEP_1 AS (
SELECT A.ID AS A_ID, A.NAME AS A_NAME, B.ID AS B_ID,
JSON_OBJECT('ID' VALUE B.ID, 'SIZE' VALUE B.SIZE) B_JSON
FROM TABLE_A A
JOIN TABLE_B B ON B.ID_A = A.ID
GROUP BY A.ID, A.NAME, B.ID, B.SIZE),
JSON_STEP_2 AS (
SELECT JSON_OBJECT ('ID' VALUE A_ID,
'NAME' VALUE A_NAME,
'B_OBJECTS' VALUE JSON_ARRAY (LISTAGG(B_JSON, ', ') WITHIN GROUP (ORDER BY B_ID) FORMAT JSON) FORMAT JSON
) JSON_OBJS
FROM JSON_STEP_1
GROUP BY A_ID, A_NAME
)
SELECT JSON_ARRAY (SELECT JSON_OBJS FROM JSON_STEP_2 FORMAT JSON) FROM SYSIBM.SYSDUMMY1;
I just updated the query with additional table TABLE_C
WITH
TABLE_A(ID,NAME) AS
(
VALUES (1, 'a')
)
, TABLE_B(ID, ID_A, SIZE) AS
(
VALUES (1, 1, 10), (1, 1, 20), (2, 1, 10), (2, 1, 20)
), TABLE_C(ID, ID_A, SIZE) AS
(
VALUES (1, 1, 5), (2,1,10), (3,1,15)
)
, JSON_STEP_1 AS
(
SELECT A_ID, A_NAME, B_ID
, JSON_OBJECT('ID' VALUE B_ID, 'SIZE' VALUE B_SIZE) B_JSON
, JSON_OBJECT('ID' VALUE C_ID, 'SIZE' VALUE C_SIZE) C_JSON
FROM
(
SELECT
A.ID AS A_ID, A.NAME AS A_NAME, B.ID AS B_ID, B.SIZE AS B_SIZE, C.ID AS C_ID, C.SIZE AS C_SIZE
, ROW_NUMBER () OVER (PARTITION BY B.ID, B.ID_A, B.SIZE) AS RN_
, ROW_NUMBER () OVER (PARTITION BY C.ID, C.ID_A, C.SIZE) AS RN1_
FROM TABLE_A A
JOIN TABLE_B B ON B.ID_A = A.ID
JOIN TABLE_C C ON C.ID_A = A.ID
)
WHERE RN_ = 1 AND RN1_ = 1
GROUP BY A_ID, A_NAME, B_ID, B_SIZE, B_ID, B_SIZE, C_ID, C_SIZE
)
, JSON_STEP_2 AS
(
SELECT
JSON_OBJECT
(
'ID' VALUE A_ID,
'NAME' VALUE A_NAME,
'B_OBJECTS' VALUE JSON_ARRAY (LISTAGG(B_JSON, ', ') WITHIN GROUP (ORDER BY B_ID) FORMAT JSON) FORMAT JSON,
'C_OBJECTS' VALUE JSON_ARRAY (LISTAGG(C_JSON, ', ') WITHIN GROUP (ORDER BY B_ID) FORMAT JSON) FORMAT JSON
) JSON_OBJS
FROM JSON_STEP_1
GROUP BY A_ID, A_NAME
)
SELECT JSON_ARRAY (SELECT JSON_OBJS FROM JSON_STEP_2 FORMAT JSON) FROM SYSIBM.SYSDUMMY1
The output should be like
{
"ID": 1,
"NAME": "a",
"B_OBJECTS": [{
"ID": 1,
"SIZE": 10
},
{
"ID": 1,
"SIZE": 20
},
{
"ID": 2,
"SIZE": 10
},
{
"ID": 2,
"SIZE": 20
}
],
"C_OBJECTS": [{
"ID": 1,
"SIZE": 5
},
{
"ID": 2,
"SIZE": 10
},
{
"ID": 3,
"SIZE": 15
}
]
}

Answer 1

WITH
TABLE_A (ID,NAME) AS
(
VALUES (1, 'a')
)
, TABLE_B (ID, ID_A, SIZE) AS
(
VALUES (1, 1, 10), (1, 1, 10), (2, 1, 10), (2, 1, 20)
)
, TABLE_C (ID, ID_A, SIZE) AS
(
VALUES (1, 1, 5), (2, 1, 10), (3, 1, 15)
)
SELECT
JSON_OBJECT
(
'ID' VALUE A.ID
, 'NAME' VALUE A.NAME
, 'B_OBJECTS' VALUE
JSON_ARRAY
(
(
SELECT JSON_OBJECT ('ID' VALUE ID, 'SIZE' VALUE SIZE FORMAT JSON)
FROM TABLE (SELECT DISTINCT ID, SIZE FROM TABLE_B B WHERE B.ID_A = A.ID ORDER BY ID)
)
FORMAT JSON
) FORMAT JSON
, 'C_OBJECTS' VALUE
JSON_ARRAY
(
(
SELECT JSON_OBJECT ('ID' VALUE ID, 'SIZE' VALUE SIZE FORMAT JSON)
FROM TABLE (SELECT DISTINCT ID, SIZE FROM TABLE_C C WHERE C.ID_A = A.ID ORDER BY ID)
)
FORMAT JSON
) FORMAT JSON
) JSON_OBJ
FROM TABLE_A A
{
"ID":1,"NAME":"a"
,"B_OBJECTS":
[
{"ID":1,"SIZE":10},
{"ID":2,"SIZE":10},
{"ID":2,"SIZE":20}
]
,"C_OBJECTS":
[
{"ID":1,"SIZE":5},
{"ID":2,"SIZE":10},
{"ID":3,"SIZE":15}
]
}