sql - 将三列合并为一列

Question

我有如下的sql语句:

SELECT p.id, p.first_name, p.last_name, a.admitted_at,
       a.discharged_at, c.name as client_name, p.receive_reminders,
       p.opt_in_to_receive_reminders, u.phone_number, p.status,
       c.id as client_id, p.mrn
  FROM patients p
  LEFT JOIN admissions a ON p.last_admission_id = a.id
  INNER JOIN facilities f ON f.id = p.facility_id
  INNER JOIN clients c ON c.id = f.client_id
  LEFT OUTER JOIN users u ON p.user_id = u.id;

我有三列:

p.opt_in_to_receive_reminders - boolean
u.phone_number - string
p.receive_reminders - boolean

我想将这 3 列的结果合并到一个虚拟列中 - messaging。例如，如果 p.opt_in_to_receive_reminders 为真且 u.phone_number 不为空且 p.receive_reminders 为真，则此列将具有真值，在其他情况下它将返回 false。

我如何在 PostgreSQL 中执行此操作？

Answer 1

就这么写吧

p.opt_in_to_receive_reminders is true and if u.phone_number is not empty and p.receive_reminders is true

作为

select p.opt_in_to_receive_reminders and u.phone_number is not null and p.receive_reminders
-- or
select p.opt_in_to_receive_reminders and u.phone_number <> '' and p.receive_reminders
-- or
select p.opt_in_to_receive_reminders and coalesce(u.phone_number, '') is null and p.receive_reminders