Postgres的加入JSON名單

Question

我在加盟Postgres的一個JSON清單問題9.4

這裏是我的問題：

表結構：

CREATE TABLE players 
(
    id serial NOT NULL, 
    player json, 
    CONSTRAINT players_pkey PRIMARY KEY (id) 
) 

CREATE TABLE matches 
(
    id serial NOT NULL, 
    match json, 
    CONSTRAINT matches_pkey PRIMARY KEY (id) 
) 

樣本數據：

players 
1;"{"Name":"AAA","Height":186,"Weight":65}" 
2;"{"Name":"BBB","Height":195,"Weight":85}" 
3;"{"Name":"CCC","Height":175,"Weight":72}" 
4;"{"Name":"DDD","Height":168,"Weight":56}" 

matches 
5;{"Id":1,"Teams":[{"Name":"TeamA","Players":[{"Name":"AAA"},{"Name":"BBB"}]},{"Name":"TeamB","Players":[{"Name":"CCC"},{"Name":"DDD"}]}],"TeamRank":[1,2]} 
6;{"Id":2,"Teams":[{"Name":"TeamA","Players":[{"Name":"CCC"},{"Name":"BBB"}]},{"Name":"TeamB","Players":[{"Name":"AAA"},{"Name":"DDD"}]}],"TeamRank":[1,2]} 

每支球隊的球員都是球隊上一場比賽中的球員。一種越來越球隊名稱和球員（目前球隊）的列表查詢如下：

SELECT DISTINCT ON (t.team->>'Name') t.team 
FROM matches m, json_array_elements(m.match->'Teams') t(team) 
ORDER BY t.team->>'Name', m.id DESC 

這將返回以下（隊表）：

"{"Name":"TeamA","Players":[{"Name":"CCC"},{"Name":"BBB"}]}" 
"{"Name":"TeamB","Players":[{"Name":"AAA"},{"Name":"DDD"}]}" 

我想參加每一個玩家與它們在列表中身高和體重以上的結果，這樣的輸出如下：

"{"Name":"TeamA","Players":[{"Name":"CCC","Height":175,"Weight":72},{"Name":"BBB","Height":195,"Weight":85}]}" 
"{"Name":"TeamB","Players":[{"Name":"AAA","Height":186,"Weight":65},{"Name":"DDD","Height":168,"Weight":56}]}" 

我試圖做到這一點使用INNER JOIN：

WITH u AS (SELECT DISTINCT ON (t.team->>'Name') t.team 
FROM matches m, json_array_elements(m.match->'Teams') t(team) -- FROM ABOVE!!! 
ORDER BY t.team->>'Name', m.id DESC) 

SELECT player FROM (SELECT json_array_elements(team->'Players') FROM u) AS v 
INNER JOIN players on v->>'Name'=player->>'Name'; 

這是對我想要的東西了一步，但我得到以下錯誤：

ERROR: operator does not exist: record ->> unknown 
SQL state: 42883 
Hint: No operator matches the given name and argument type(s). You might need to add explicit type casts. 
Character: 2822 

任何人都可以提出一個解決這個問題，或者另一種方式來做到這一點？

感謝

Answer 1

此：

(SELECT json_array_elements(team->'Players') FROM u) AS v 

聲明v的關係，所以v其他地方的任何引用意味着 「在這種關係的記錄」。所以這個：

v->>'Name'=player->>'Name' 

不起作用，因爲它試圖利用v作爲JSON值，而不是作爲一個記錄。

要解決此問題，您需要使用列別名;例如，你可以寫：

SELECT player FROM (SELECT json_array_elements(team->'Players') FROM u) AS v(v_player) 
INNER JOIN players on v_player->>'Name' = player->>'Name';