Question

我有一个对话表，一个会话表和一个播放器表。我想为玩家的任何一组（意思是不同的组，不考虑排序）找到一个且只有一个conversation_owned。

converation_owned列conversation_id和player_id是外键

    CREATE TABLE conversation
(
    id INTEGER PRIMARY KEY NOT NULL,
    created_at TIMESTAMP WITH TIME ZONE,
    modified_at TIMESTAMP WITH TIME ZONE,
    count INTEGER
);
CREATE UNIQUE INDEX conversation_id_uindex ON conversation (id);

CREATE TABLE conversation_owned
(
    id INTEGER PRIMARY KEY NOT NULL,
    conversation_id BIGINT DEFAULT nextval('conversation_owned_conversation_id_seq'::regclass) NOT NULL,
    player_id INTEGER,
    created_at TIMESTAMP WITH TIME ZONE,
    modified_at TIMESTAMP WITH TIME ZONE,
    CONSTRAINT conversation_owned_conversation_id_fk FOREIGN KEY (conversation_id) REFERENCES conversation (id),
    CONSTRAINT conversation_owned_player_id_fk FOREIGN KEY (player_id) REFERENCES 
);
CREATE UNIQUE INDEX conversation_owned_id_uindex ON conversation_owned (id);

CREATE TABLE player
(
    id INTEGER PRIMARY KEY NOT NULL,
    player_name TEXT NOT NULL
);

例如：如果我在iMessage或Facebook Messenger撰写窗口中键入多个联系人（Billy，Joe和Sue），该应用程序将检索我与我自己，Billy，Joe或Sue的任何现有对话，无论我的顺序如何进入他们。但如果我进入比利和乔（而不是苏），我可能会有一个不同的对话。我正在寻找能够以相对有效的方式给我这种行为的查询。

请注意，如果我将“count”列添加到会话表中，该会话表中包含会话中的参与者数量，使其如下所示：

CREATE TABLE conversation
    (
        id INTEGER PRIMARY KEY NOT NULL
    );

我可以使用此查询来获取我想要的内容，但在我看来，我应该能够在不添加和维护会话中的“计数”列的情况下执行此操作！

SELECT
  *
FROM
  conversation_owned
  INNER JOIN conversation ON conversation_owned.conversation_id=conversation.id
WHERE
  conversation_id
  NOT IN (
    SELECT
      conversation_owned.conversation_id
    FROM
      conversation_owned
    WHERE
      conversation_owned.player_id
    NOT IN (${playerIDs})
  )
AND
    conversation.count = ${participantCount}
AND
  conversation_owned.player_id = ${requestingPlayerID};

在Postgres中按集查询

0 个答案: