向查询中的两个子选择添加条件

Question

我有这个问题。

SELECT DISTINCT
    u.email,
    (
        SELECT
            count(DISTINCT o.id)
        FROM
            orders o
            INNER JOIN cart_dates cd ON cd.order_id = o.id
        WHERE
            u.id = o.user_id
    ) as total,
    (
        SELECT
            count(DISTINCT o.id)
        FROM
            orders o
            INNER JOIN cart_dates cd ON cd.order_id = o.id AND o.pre_order = TRUE
        WHERE
            u.id = o.user_id
    ) as count

FROM
    users u

如何获取行数，例如，count > (total / 2)？

Answer 1

我只是假设回答这个问题。

SELECT 
  u.email
FROM
  users u
  INNER JOIN cart_dates cd ON cd.order_id = o.id
GROUP BY
  u.email
HAVING
  COUNT(DISTINCT Case when o.pre_order = TRUE then o.id else null end) >
  (COUNT(DISTINCT o.id)/2)

我试着让它更简单。

向查询中的两个子选择添加条件

Add condition to two sub selects in query

database

postgresql

postgresql-9.4