Select query using json format value - sql

Question

If customer first_name-'Monika',
last_name='Awasthi'
Then I am using below query to return value in json format:
SELECT *
FROM
(
SELECT JSON_ARRAYAGG(JSON_OBJECT('CODE' IS '1','VALUE' IS 'Monika'||' '||'Awasthi'))
FROM DUAL
);
It is working fine & give below output:
[{"CODE":"1","VALUE":"Monika Awasthi"}]
But I want one more value which should be reversed means output should be:
[{"CODE":"1","VALUE":"Monika Awasthi"},{"CODE":"2","VALUE":"Awasthi Monika"}]
Kindly give me some suggestions. Thank You

Answer 1

Another approach is to use a CTE to generate the two codes and values; your original version could be written to get the name data from a table or CTE:
-- CTE for sample data
WITH cte (first_name, last_name) AS (
SELECT 'Monika', 'Awasthi' FROM DUAL
)
-- query against CTE or table
SELECT JSON_ARRAYAGG(JSON_OBJECT('CODE' IS '1','VALUE' IS last_name ||' '|| first_name))
FROM cte;
And you could then extend that with a CTE that generates the value with the names in both orders:
WITH cte1 (first_name, last_name) AS (
SELECT 'Monika', 'Awasthi' FROM DUAL
),
cte2 (code, value) AS (
SELECT 1 AS code, first_name || ' ' || last_name FROM cte1
UNION ALL
SELECT 2 AS code, last_name || ' ' || first_name FROM cte1
)
SELECT JSON_ARRAYAGG(JSON_OBJECT('CODE' IS code,'VALUE' IS value))
FROM cte2;
which gives:
JSON_ARRAYAGG(JSON_OBJECT('CODE'ISCODE,'VALUE'ISVALUE))
-------------------------------------------------------------------------
[{"CODE":1,"VALUE":"Monika Awasthi"},{"CODE":2,"VALUE":"Awasthi Monika"}]
db<>fiddle

Answer 2

A simple logic through use of SQL(without using PL/SQL) in order to generate code values as only be usable for two columns as in this case might be
SELECT JSON_ARRAYAGG(
JSON_OBJECT('CODE' IS tt.column_id,
'VALUE' IS CASE WHEN column_id=1
THEN name||' '||surname
ELSE surname||' '||name
END)
) AS result
FROM t
CROSS JOIN (SELECT column_id FROM user_tab_cols WHERE table_name = 'T') tt
where t is a table which hold name and surname columns
Demo
More resilient solution might be provided through use of PL/SQL, even more columns exist within the data source such as
DECLARE
v_jso VARCHAR2(4000);
v_arr OWA.VC_ARR;
v_arr_t JSON_ARRAY_T := JSON_ARRAY_T();
BEGIN
FOR c IN ( SELECT column_id FROM user_tab_cols WHERE table_name = 'T' )
LOOP
SELECT 'JSON_OBJECT( ''CODE'' IS '||MAX(c.column_id)||',
''VALUE'' IS '||LISTAGG(column_name,'||'' ''||')
WITHIN GROUP (ORDER BY ABS(column_id-c.column_id))
||' )'
INTO v_arr(c.column_id)
FROM ( SELECT * FROM user_tab_cols WHERE table_name = 'T' );
EXECUTE IMMEDIATE 'SELECT '||v_arr(c.column_id)||' FROM t' INTO v_jso;
v_arr_t.APPEND(JSON_OBJECT_T(v_jso));
END LOOP;
DBMS_OUTPUT.PUT_LINE(v_arr_t.STRINGIFY);
END;
/
Demo

Answer 3

As I explained in a comment under your question, I am not clear on how you define the CODE values for your JSON string (assuming you have more than one customer).
Other than that, if you need to create a JSON array of objects from individual strings (as in your attempt), you probably need to use JSON_ARRAY rather than JSON_ARRAYAGG. Something like I show below. Incidentally, I also don't know why you needed to SELECT * FROM (subquery) - the outer SELECT seems entirely unnecessary.
So, if you don't actually aggregate over a table, but just need to build a JSON array from individual pieces:
select json_array
(
json_object('CODE' is '1', 'VALUE' is first_name || ' ' || last_name ),
json_object('CODE' is '2', 'VALUE' is last_name || ' ' || first_name)
) as result
from ( select 'Monika' as first_name, 'Awasthi' as last_name from dual )
;
RESULT
------------------------------------------------------------------------------
[{"CODE":"1","VALUE":"Monika Awasthi"},{"CODE":"2","VALUE":"Awasthi Monika"}]