SQL Oracle 汇总表查询，每组有前 n 个

Question

我有两张这样的桌子

交易表CustID | fk 到客户表，金额| 每笔交易花费的金额

客户表CustID | pk,年龄| 客户年龄

我需要进行查询以按年龄范围对客户进行分组或分桶，并且我需要使每个年龄组的前 3 名金额最高，以及到目前为止我所做的最低 3 金额或最低消费金额是https://dbfiddle。英国/?rdbms=oracle_11.2&fiddle=ccf988ec525dc133cf7825ba052e8054

到目前为止我管理的内部查询

我曾尝试使用 CTE，但仍然不确定如何使用cte获得每组的前 3 名/每组的后 3 名

问题出在第一行的第一张图片上，回报超过 3/他们附加所有记录，而我只需要前 3 个

感谢您的帮助

Answer 1

您可以使用ROW_NUMBER()分析函数来查找最高和最低，然后您可以使用LISTAGG中的条件聚合仅在其相应列表中显示最高和最低：

select age_bucket, 
       LISTAGG(CASE WHEN max_rn <= 3 THEN amount END, ',')
         WITHIN GROUP (ORDER BY amount DESC) AS TOP_3_AMOUNT,
       LISTAGG(CASE WHEN min_rn <= 3 THEN amount END, ',')
         WITHIN GROUP (ORDER BY amount ASC ) AS BOTTOM_3_AMOUNT
FROM   (
  SELECT amount,
         age_bucket,
         ROW_NUMBER() OVER (PARTITION BY age_bucket ORDER BY amount DESC) AS max_rn,
         ROW_NUMBER() OVER (PARTITION BY age_bucket ORDER BY amount ASC ) AS min_rn
  FROM   (
    select t.amount,
           case
           when c.age <= 20             THEN '<= 20'
           when c.age between 21 and 30 THEN '21-30'
           when c.age between 31 and 40 THEN '31-40'
           when c.age between 41 and 50 THEN '41-50'
           when c.age >= 51             THEN '>= 51'
           END as age_bucket 
    from   transaction t
           join customer c on t.cust_id=c.cust_id
  )
)
WHERE max_rn <= 3
OR    min_rn <= 3
group by age_bucket
order by age_bucket asc;

db<> 在这里摆弄

---

我需要将其设置为仅由客户 ID 区分的前 3 名或后 3 名

select age_bucket, 
       LISTAGG(CASE WHEN max_rn <= 3 THEN amount END, ',')
         WITHIN GROUP (ORDER BY amount DESC) AS TOP_3_AMOUNT,
       LISTAGG(CASE WHEN min_rn <= 3 THEN amount END, ',')
         WITHIN GROUP (ORDER BY amount ASC ) AS BOTTOM_3_AMOUNT
FROM   (
  SELECT amount,
         age_bucket,
         CASE max_cust_rn
         WHEN 1
         THEN ROW_NUMBER() OVER (PARTITION BY age_bucket ORDER BY amount DESC)
         END AS max_rn,
         CASE min_cust_rn
         WHEN 1
         THEN ROW_NUMBER() OVER (PARTITION BY age_bucket ORDER BY amount ASC )
         END AS min_rn
  FROM   (
    SELECT amount,
           age_bucket,
           ROW_NUMBER() OVER (
             PARTITION BY age_bucket, cust_id ORDER BY amount DESC) AS max_cust_rn,
           ROW_NUMBER() OVER (
             PARTITION BY age_bucket, cust_id ORDER BY amount ASC ) AS min_cust_rn
    FROM   (
      select t.amount,
             t.cust_id,
             case
             when c.age <= 20             THEN '<= 20'
             when c.age between 21 and 30 THEN '21-30'
             when c.age between 31 and 40 THEN '31-40'
             when c.age between 41 and 50 THEN '41-50'
             when c.age >= 51             THEN '>= 51'
             END as age_bucket 
      from   transaction t
             join customer c on t.cust_id=c.cust_id
    )
  )
  WHERE max_cust_rn = 1
  OR    min_cust_rn = 1
)
WHERE max_rn <= 3
OR    min_rn <= 3
group by age_bucket
order by age_bucket asc;

db<> 在这里摆弄

Answer 2

因为没有表的描述，我只是试着改了一点，你可以试试：

SELECT   age_bucket,
         Listagg(
         CASE
                  WHEN seqnumbyeachcusttop = 1 THEN amount
         END, ',') within GROUP (ORDER BY amount DESC)            AS test_top_3_amouny,
         listagg(amount, ',') within GROUP (ORDER BY amount DESC) AS top_3_principal
FROM     (
                  SELECT   age_bucket,
                           seqnumbyeachcusttop,
                           amount,
                           row_number() OVER (partition BY amount ORDER BY amount DESC) rn
                  FROM     (
                                    SELECT   t.amount                                                          AS amount,
                                             t.cust_id                                                         AS cust_id,
                                             row_number() OVER (partition BY t.cust_id ORDER BY t.amount DESC) AS seqnumbyeachcusttop,
                                             CASE
                                                      WHEN c.age <= 20 THEN ' <= 20'
                                                      WHEN c.age BETWEEN 21 AND      30 THEN '21-30'
                                                      WHEN c.age BETWEEN 31 AND      40 THEN '31-40'
                                                      WHEN c.age BETWEEN 41 AND      50 THEN '41-50'
                                                      WHEN c.age >= 51 THEN '>= 51'
                                             END AS age_bucket
                                    FROM     TRANSACTION t
                                    JOIN     customer c
                                    ON       t.cust_id=c.cust_id ))
WHERE    rn <= 3) GROUP BY age_bucket ORDER BY age_bucket ASC;