如果我有一个名为“races”的简单表,使用
postgresql 9.3(和新的json awesomness),它有两列描述,如：
race-id integer,race-data json
而且,json是每个种族的有效载荷
{ "race-time": some-date,"runners": [ { "name": "fred","age": 30,"position": 1 },{ "name": "john","age": 29,"position": 3 },{ "name": "sam","age": 31,"position": 2 } ],"prize-money": 200 }
如何查询表格：
1)sam已经到来的比赛1
2)sam已经来到第1名,约翰已经来到第2名
3)年龄大于30岁的跑步者人数> 5和奖金> 5000
到目前为止,我的实验(特别是查询嵌套阵列有效载荷)导致进一步使数据正常化,即创建一个名为跑步者的表来进行这种查询.理想情况下,我想使用这个新的fangled json查询awesomeness,但我似乎无法做出头或尾部相应的3个简单的查询.
您可以将json放在一个记录中,然后根据需要进行查询(参见
json functions)：
with cte as (
select
race_id,json_array_elements(r.race_data->'runners') as d,(r.race_data->>'prize-money')::int as price_money
from races as r
),cte2 as (
select
race_id,price_money,max(case when (d->>'position')::int = 1 then d->>'name' end) as name1,max(case when (d->>'position')::int = 2 then d->>'name' end) as name2,max(case when (d->>'position')::int = 3 then d->>'name' end) as name3
from cte
group by race_id,price_money
)
select *
from cte2
where name1 = 'sam' and name2 = 'john'
由于您的JSON结构,这有点复杂.我认为,如果你改变你的结构,你的查询可能会更简单：
{
"race-time": some-date,"runners":
{
"1": {"name": "fred","age": 30},"2": {"name": "sam","age": 31},"3": {"name": "john","age": 29}
},"prize-money": 200
}
您可以使用 – >>和 – >运算符或json_extract_path_text函数来获取所需的数据,然后在where子句中使用它：
select *
from races as r
where
r.race_data->'runners'->'1'->>'name' = 'sam';
select *
from races as r
where
json_extract_path_text(r.race_data,'runners','1','name') = 'sam' and
json_extract_path_text(r.race_data,'2','name') = 'john';
select *
from races as r
where
(r.race_data->>'prize-money')::int > 100 and
(
select count(*)
from json_each(r.race_data->'runners')
where (value->>'age')::int >= 30
) >= 2
