plpgsql 编程 - JSON数组循环

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背景

PostgreSQL的plpgsql编程语言和Oracle PL/SQL编程语言类似,是功能很强大的数据库编程语言。

JSON是PG支持的非结构化类型,那么如何在PLPGSQL中LOOP JSON数组呢?

https://www.postgresql.org/docs/9.6/static/plpgsql-control-structures.html#PLPGSQL-FOREACH-ARRAY

例子

例子1

postgres=# do language plpgsql $$  
declare  
  rec jsonb;  
begin  
  for rec in select jsonb_array_elements('[{"lat":30.27699965,"lng":120.02319424},{"lat":30.27700545,"lng":120.02321551}]')                     
  loop  
    raise notice '%', rec;  
  end loop;  
end;  
$$;  
NOTICE:  {"lat": 30.27699965, "lng": 120.02319424}  
NOTICE:  {"lat": 30.27700545, "lng": 120.02321551}  
DO  

例子2

DO  
$BODY$  
DECLARE  
    omgjson json := '[{ "type": false }, { "type": "photo" }, {"type": "comment" }]';  
    i json;  
BEGIN  
  FOR i IN SELECT * FROM json_array_elements(omgjson)  
  LOOP  
    RAISE NOTICE 'output from space %', i->>'type';  
  END LOOP;  
END;  
$BODY$ language plpgsql  

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