Question

我想在Postgres中使用SQL来提取数据，但是想进入JSON结果并且只提取我需要的数据。

如果我写（在Valentina工作室）：

Select "data" from "cars"

第一行看起来像：

[{"Model": "Golf", "Make": "VW", "Engine": "2.9"}, 
{"Model": "M3", "Make": "BMW", "Engine": "3.0"}]

我想要的只是：

Golf, M3或"Golf", "M3"

然后我也可以对"Make"或"Engine"

使用相同的方法

基本上我不希望我的结果是JSON。

Answer 1

SELECT string_agg(x->>'Model', ',')
FROM cars
   CROSS JOIN LATERAL
      jsonb_array_elements(data) x
GROUP BY cars;

┌────────────┐
│ string_agg │
├────────────┤
│ Golf,M3    │
└────────────┘
(1 row)

Answer 2

使用json_array_elements()：

with cars(data) as (
values
    ('[
        {"Model": "Golf", "Make": "VW", "Engine": "2.9"}, 
        {"Model": "M3", "Make": "BMW", "Engine": "3.0"}
    ]'::json)
)

select 
    elem->>'Model' as model,
    elem->>'Make' as make,
    elem->>'Engine' as engine
from cars,
lateral json_array_elements(data) elem

 model | make | engine 
-------+------+--------
 Golf  | VW   | 2.9
 M3    | BMW  | 3.0
(2 rows)

Answer 3

我想我也得到了我想要的东西（并按照我计划的方式融化）：

    select obj->'Model' as model, obj->'Make' as make, 
obj->'Engine' as engine from data n, jsonb_array_elements(n.DATA) as obj

从上面我也可以使用：

select 
    elem->>'Model' as model,
    elem->>'Make' as make ,
    elem->>'Engine' as engine
from cars,
lateral jsonb_array_elements(data) elem;

感谢您的帮助！

在JSON

3 个答案: