SQL從表列值中選擇子查詢IN

Question

首先，對於可能無法正確表達問題標題表示歉意，我對SQL查詢不太瞭解。

我有一個表「停車場」的列這樣的

| days_2  | from_hr | to_hr 
"1,2,3,4,5"  "08:00:00" "18:00:00" 
"0,1,2,3,4,5,6" "08:00:00" "22:00:00" 
... 
... 

我做了一個查詢這是工作確定：

SELECT Extract(dow from current_timestamp::DATE) as Day, 
    current_time BETWEEN from_hr and to_hr as ParkHour, 
    days_2, 
    from_hr, 
    to_hr 
FROM public.parkings; 

如果今天是星期一和當前時間是21:26 ：00結果爲：

day | ParkHour | days_2  | from_hr | to_hr 
1 f   "1,2,3,4,5"  "08:00:00" "18:00:00" 
1 t   "0,1,2,3,4,5,6" "08:00:00" "22:00:00" 
... 
... 

我想修改這個查詢的方式，在第一列將被存儲res ULT（真/假），如果目前的日數爲表列DAYS_2該記錄，在這樣

SELECT Extract(dow from current_timestamp::DATE) in (1,2,3,4,5,6); 

的路要走，如果它現在是星期天其中（0）例如最終結果將是假的第一排，但在第二排是真的：

day | ParkHour | days_2  | from_hr | to_hr 
f f   "1,2,3,4,5"  "08:00:00" "18:00:00" 
t t   "0,1,2,3,4,5,6" "08:00:00" "22:00:00" 

我該如何做到這一點？

謝謝！

Answer 1

select 
    extract(dow from now()) 
    = 
    any (regexp_split_to_array('1,2,3', ',')::integer[]); 
?column? 
---------- 
t 

將該列類型轉換爲數組將避免字符串拆分步驟。

http://www.postgresql.org/docs/current/static/arrays.html

Answer 2

嘗試

select 
    case 
    when Extract(dow from current_timestamp::DATE) = '0' then 't' else 'f' 
    when Extract(dow from current_timestamp::DATE) = '1' then 't' else 'f' 
    when Extract(dow from current_timestamp::DATE) = '2' then 't' else 'f' 
    when Extract(dow from current_timestamp::DATE) = '3' then 't' else 'f' 
    when Extract(dow from current_timestamp::DATE) = '4' then 't' else 'f' 
    when Extract(dow from current_timestamp::DATE) = '5' then 't' else 'f' 
    when Extract(dow from current_timestamp::DATE) = '6' then 't' else 'f' 
    end as day, 
    current_time BETWEEN from_hr and to_hr as ParkHour, 
    days_2, 
    from_hr, 
    to_hr 
from public.parkings; 

正如其他人所提到的，它會更容易，如果你的表結構是和/或如果使用數組更好。

HTH