Postgres 12

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CREATE TABLE tab ( id INT, jsdata JSONB);
 INSERT INTO tab VALUES 
 (1, '[
  {"name":"test","age":"21","phone":"6589","town":"54"},
  {"name":"test12","age":"67","phone":"6546","town":"54"}
]')
 

CREATE TABLE



INSERT 0 1


WITH s AS
(
 SELECT ('{'||idx-1||',phone}')::text[] AS path_phone,
        ('{'||idx-1||',town}')::text[] AS path_town,
        ('{'||idx-1||',age}')::text[] AS path_age
   FROM tab 
  CROSS JOIN jsonb_array_elements(jsdata) 
   WITH ORDINALITY arr(j,idx)
  WHERE j->>'name'='test' 
)
UPDATE tab
   SET jsdata = jsonb_set(jsonb_set(
                          jsonb_set(jsdata,
                                          s.path_phone,'"1111"',false),
                          path_town,'"55"',false),
                          s.path_age,'"20"',false
                          )
  FROM s
  

UPDATE 1


SELECT *
  FROM tab
 


id
jsdata


1
[{"age": "20", "name": "test", "town": "55", "phone": "1111"}, {"age": "67", "name": "test12", "town": "54", "phone": "6546"}]



SELECT 1