Question

我正在尝试进行群组分析 - 尝试计算保留率。这是我的代码：

SELECT 
  renter_id,
  min(DATE_PART('year', created_at)) AS first_rental_year,
  DATE_PART('year', created_ay) AS y1,
  round(100 * count(distinct b2.renter_id) /
    count(distinct b1.renter_id)) AS retention      
FROM bookings AS b1
  LEFT JOIN bookings AS b2 ON
    b1.renter_id = b2.renter_id
    AND DATE_PART('year', b1.created_at) = DATE_PART(datetime('year', b2.created_at, '-1 year'))
GROUP BY  1
ORDER BY 2;

它根本不起作用...... The error message I get says: Hint: No function matches the given name and argument types. You might need to add explicit type casts.

一些建议会很棒。

Answer 1

直接问题在于PostgreSQL中不存在的datetime()函数。然后是别名和聚合的一些问题。这可以让你更接近你想要的地方：

SELECT 
  b1.renter_id,
  min(DATE_PART('year', b1.created_at)) AS first_rental_year,
  DATE_PART('year', created_ay) AS y1,            -- Needs an aggregate
  round(100. * count(distinct b2.renter_id) /     -- Use float, see 100.
    count(distinct b1.renter_id)) AS retention
FROM bookings AS b1
LEFT JOIN bookings AS b2
  ON  b1.renter_id = b2.renter_id
  AND extract(year, b1.created_at) + 1 = extract(year, b2.created_at)
GROUP BY 1
ORDER BY 2;

但是，您的群组功能的逻辑有缺陷。您应该将问题编辑为：

更详细地解释您希望如何计算保留期
添加表格结构和一些示例数据
显示预期结果。

SQL中的年度队列分析

1 个答案: