在合併三列到一個

Question

我有以下SQL語句：

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 

我想這3列的結果結合起來，一個虛擬列 - messaging。例如，如果p.opt_in_to_receive_reminders爲真，並且u.phone_number不爲空，並且p.receive_reminders爲真，那麼此列將具有真值，在其他情況下它將返回false。

我該如何在PostgreSQL中做到這一點？

Answer 1

就這樣寫：

p.opt_in_to_receive_reminders是真實的，如果u.phone_number是不是空的，p.receive_reminders是真的

爲

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