Question

我有一个由两级数组组成的json，如：

[
  {
    name: "Group one",
    races: 
    [
     {name: "Race 1"},
     {name: "Race 2"},
    ]
  },
  {
    name: "Group two",
    races: 
    [
     {name: "Race 10"},
     {name: "Race 11"},
    ]
  }
]

是否可以通过魔术SQL获得：

group_num | race_num | race
int       | int      | json
1         | 1        | {name: "Race 1"}
1         | 2        | {name: "Race 2"}
2         | 1        | {name: "Race 10"}
2         | 2        | {name: "Race 11"}

其中：

group_num是其数组中每个组的排名
race_num是其数组中每个种族的等级

我认为这可能与json_array_elements(json)和row_number() OVER ()有关，但我无法确定如何做到正确！

Answer 1

with my_table(data) as (
values(
'[
  {
    "name": "Group one",
    "races": 
    [
     {"name": "Race 1"},
     {"name": "Race 2"}
    ]
  },
  {
    "name": "Group two",
    "races": 
    [
     {"name": "Race 10"},
     {"name": "Race 11"}
    ]
  }
]'::json)
)
select 
    group_num, 
    rank() over (partition by group_num order by value->>'name') as race_num,
    value as race
from (
    select 
        rank() over (order by value->>'name') as group_num, 
        value as grp
    from my_table,
    json_array_elements(data)
    ) s,
json_array_elements(grp->'races');

结果：

 group_num | race_num |        race         
-----------+----------+---------------------
         1 |        1 | {"name": "Race 1"}
         1 |        2 | {"name": "Race 2"}
         2 |        1 | {"name": "Race 10"}
         2 |        2 | {"name": "Race 11"}
(4 rows)

注意，您的json无效，请使用jsonlint来验证json表达式。

使用json_array_elements（json）并获取项目排名

1 个答案: