SQL从表列值中选择子查询IN

Question

首先，对可能无法正确表达问题的标题表示歉意，我对SQL查询不是很满意。

我有一个表“停车场”，像这样的列

| 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"
...
...

我做了下一个查询，它工作正常：

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，当前时间是21:26:00，则结果为：

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"
...
...

我想以如下方式修改此查询：如果当前天数在该记录的表列days_2中，则在第一列中将存储结果（是/ 否） ，方式是这样的

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

例如，如果现在是星期天（0），则第一行的最终结果为false，而第二行的结果为true：

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"

我怎样才能做到这一点？

谢谢！

Answer 1

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

将该列类型转换为数组将避免字符串拆分步骤。

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

Answer 2

尝试

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;

正如其他人提到的那样，如果您的表结构更好和/或使用数组，会更容易。

高温超导