Postgres 12

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CREATE TABLE billing_2012_08(b_id int, billingcode text);
INSERT INTO  billing_2012_08 VALUES
  (1,  'blah1')
 ,(2,  'blah1')
 ,(3,  'blah1')
 ,(4,  'blah4')
 ,(5,  'blah5')
 ,(6,  'blah6')
 ,(7,  'blah7')
 ,(8,  'blah8')
 ,(9,  'blah9')
 ,(10, 'blah10')
 ,(11, 'blah11');

CREATE TABLE sending_response_2012_08(s_id int, charged numeric);
INSERT INTO  sending_response_2012_08 VALUES
  (1,  1.2)
 ,(2,  2.3)
 ,(3,  3.4)
 ,(4,  4.5)
 ,(5,  5.6)
 ,(6,  6.7)
 ,(7,  7.8)
 ,(8,  8.9)
 ,(9,  9.0)
 ,(10, 10)
 ,(11, 11);
 
11 rows affected

11 rows affected

-- UNION with text
SELECT json_col::json
FROM (
   (
   SELECT '{"billingcode" : "' || billingcode || '"}'::text AS json_col
   FROM   billing_2012_08
   LIMIT  10
   )
   UNION
   (
   SELECT '{"charged" : "' || charged || '"}'::text
   FROM   sending_response_2012_08
   LIMIT  10
   )
   ) sub;
-- ORDER  BY 1;  -- not possible with json!


json_col


{"charged" : "1.2"}

{"billingcode" : "blah6"}

{"charged" : "7.8"}

{"billingcode" : "blah9"}

{"charged" : "2.3"}

{"billingcode" : "blah7"}

{"charged" : "8.9"}

{"charged" : "10"}

{"billingcode" : "blah1"}

{"charged" : "9.0"}

{"billingcode" : "blah4"}

{"charged" : "3.4"}

{"charged" : "5.6"}

{"charged" : "4.5"}

{"billingcode" : "blah8"}

{"billingcode" : "blah10"}

{"billingcode" : "blah5"}

{"charged" : "6.7"}


-- UNION with jsonb
SELECT to_jsonb(t) AS jsonb_col
FROM  (SELECT billingcode FROM billing_2012_08 LIMIT 10) t

UNION
SELECT to_jsonb(t)  -- also preserves numeric type!
FROM  (SELECT charged FROM sending_response_2012_08 LIMIT 10) t

ORDER  BY 1;  -- possible with jsonb


jsonb_col


{"billingcode": "blah1"}

{"billingcode": "blah10"}

{"billingcode": "blah4"}

{"billingcode": "blah5"}

{"billingcode": "blah6"}

{"billingcode": "blah7"}

{"billingcode": "blah8"}

{"billingcode": "blah9"}

{"charged": 1.2}

{"charged": 2.3}

{"charged": 3.4}

{"charged": 4.5}

{"charged": 5.6}

{"charged": 6.7}

{"charged": 7.8}

{"charged": 8.9}

{"charged": 9.0}

{"charged": 10}