使用每周日期对用户进行排名并列出所有排名第一的用户

Question

我有一个名为 coupons 的表，其架构如下：

CREATE TABLE "public"."coupons" (
   "id" int4 NOT NULL,
    "suprise" bool NOT NULL DEFAULT false,
    "user_id" int4 NOT NULL,
    "start" timestamp NOT NULL,
    "win_price" numeric(8,2) NOT NULL DEFAULT 0::numeric,
    "fold" int4 NOT NULL DEFAULT 3,
    "pay" numeric(8,2) NOT NULL DEFAULT 0::numeric,
    "rate" numeric(8,2) NOT NULL DEFAULT 0::numeric,
    "win" varchar(255) NOT NULL DEFAULT 'H'::character varying COLLATE "default",
    "end" timestamp NOT NULL,
    "win_count" int4 NOT NULL DEFAULT 0,
    "match_count" int4 NOT NULL DEFAULT 0,
    "played" bool NOT NULL DEFAULT false,
    "created_at" timestamp NOT NULL,
    "updated_at" timestamp NOT NULL
)
WITH (OIDS=FALSE);

为了对win_price weekly 的用户进行排名，我编写了下面的查询以获得 27-07-2015 和 03-08-2015 之间的前 5 名：

SELECT ROW_NUMBER() OVER(ORDER BY sum(win_price) DESC) AS rnk,
       sum(win_price) AS win_price, user_id,
       min(created_at) min_create
FROM coupons
WHERE played = true AND win = 'Y'
AND created_at BETWEEN '27-07-2015' AND '03-08-2015'
GROUP BY user_id
ORDER BY rnk ASC
LIMIT 5;

我正在寻找一个新的查询，它每周但在给定的日期期间列出排名第一的用户。
即：2015 年 1 月 9 日至 2015 年 9 月 30 日期间：

rnk - win_price - user_id - min_create 1 - 1.52 - 1 - .........（第一周） 1 - 10.92 - 2 - .........（发送周） 1 - 11.23 - 1 - .........（第三周等）

Answer 1

SELECT *
FROM  (
   SELECT date_trunc('week', created_at) AS week
        , rank() OVER (PARTITION BY date_trunc('week', created_at)
                       ORDER BY sum(win_price) DESC NULLS LAST) AS rnk
        , sum(win_price) AS win_price
        , user_id
        , min(created_at) min_create
   FROM   coupons
   WHERE  played = true
   AND    win = 'Y' AND created_at BETWEEN '27-07-2015' AND '03-08-2015'
   GROUP  BY 1, 4  -- reference to 1st & 4th column
   ) sub
WHERE  rnk = 1
ORDER  BY week;

这将返回每周的获胜用户 - 拥有最多 sum(win_price) 的用户。

请注意，我使用的是 rank() instead of row_number()，因为您没有为每周的多个获胜者定义决胜局。

还要注意排序子句DESC NULLS LAST：这可以防止 NULL 值首先排序（如果你应该有 NULL）：

• PostgreSQL sort by datetime asc, null first?

星期由起始时间戳表示，您可以使用to_char() 任意设置格式。

查询的关键元素：您可以使用窗口函数而不是聚合函数。详情：

• Postgres window function and group by exception

考虑SELECT 查询中的事件顺序：

• Best way to get result count before LIMIT was applied