我需要从一个包含空间信息的json文件中提取数据。该文件的内容如下:
{"vertices":[{"lat":46.744628268759314,"lon":6.569952920654968},
{"lat":46.74441692818192,"lon":6.570487107359068},
{"lat":46.74426116111054,"lon":6.570355867853787},
{"lat":46.74447250168793,"lon":6.569821681149689}],
"name":"demo-field",
"cropType":"sugarbeet",
"cropPlantDistance":0.18000000715255737,
"rowDistance":0.5,"numberOfRows":[28,12,12],"seedingDate":"2016-08-17T07:39+00:00"}
我已经创建了一个表格,然后将该文件的内容复制到其中。
create table field(data json);
COPY field(data) FROM '/home/guest-pc5/field.json';
我现在可以查询我的数据
SELECT json_array_elements(data->'vertices') from field;
{"lat":46.744628268759314,"lon":6.569952920654968}
{"lat":46.74441692818192,"lon":6.570487107359068}
{"lat":46.74426116111054,"lon":6.570355867853787}
{"lat":46.74447250168793,"lon":6.569821681149689}
(4 rows)
问题是我不能像那样使用它。我想要捕获“lat”和“lon”的值并将它们放入字段表中。
我尝试使用函数json_to_recordset,但没有成功。
select * from json_to_recordset('[{"lat":46.744628268759314,"lon":6.569952920654968},{"lat":46.74441692818192,"lon":6.570487107359068},{"lat":46.74426116111054,"lon":6.570355867853787},{"lat":46.74447250168793,"lon":6.569821681149689}]') as (lat numeric, lon numeric);
ERROR: function json_to_recordset(unknown) does not exist
LINE 1: select * from json_to_recordset('[{"lat":46.744628268759314,...
^
HINT: No function matches the given name and argument types. You might need to add explicit type casts.