PHP:在多维数组中找到字符串，还是返回空数组键？

Question

我有一个多维数组$rows，它返回如下所示的结果；我创建了基于array_keys的查询。现在我面临的问题是，如果没有空床，并且我的所有查询都被抛出，$rows可能会返回一些行，也可能不会返回。

我尝试过使用in_array函数，但这似乎不适用于多维数组。

array (size=6)
      0 => 
        array (size=2)
          'room_category' => string 'MALE GENERAL WARD' (length=17)
          'vacant_beds' => string 'MG-5' (length=4)
      1 => 
        array (size=2)
          'room_category' => string 'FEMALE GENERAL WARD' (length=19)
          'vacant_beds' => string 'FG-2,FG-3,FG-4' (length=14)
      2 => 
        array (size=2)
          'room_category' => string 'MOTHER CHILD WARD' (length=17)
          'vacant_beds' => string 'MC-1,MC-3,MC-4' (length=14)
      3 => 
        array (size=2)
          'room_category' => string 'NICU' (length=4)
          'vacant_beds' => string 'NICU-8,NICU-4,NICU-5,NICU-6,NICU-1,NICU-7,NICU-2' (length=48)
      4 => 
        array (size=2)
          'room_category' => string 'CLASSIC' (length=7)
          'vacant_beds' => string 'CL-9,CL-4,CL-5,CL-7,CL-8' (length=24)
      5 => 
        array (size=2)
          'room_category' => string 'DELUXE' (length=6)
          'vacant_beds' => string 'DLX-6,DLX-3,DLX-4,DLX-5' (length=23)

我应该采取什么方法，或确保它返回一行，即使一个特定的病房不是空置的。

我为$rows编写的代码如下：

select `rct`.`room_category` AS `room_category`,
    group_concat(`rn`.`room_name` separator ',') AS `vacant_beds` 
    from ((`room_name` `rn` join `room_category` 
    `rct` on((`rn`.`room_category` = `rct`.`id`))) 
    left join `patient_detail` `pd` on(((`rn`.`id` = `pd`.`bed_type`) 
    and (isnull(`pd`.`discharge_date`) or (now() between `pd`.`admission_date` and `pd`.`discharge_date`))))) 
    where isnull(`pd`.`id`) group by `rn`.`room_category`

Answer 1

您对空床查询的连接忽略了空值。我建议您使用子查询生成完整的room_category值列表。

            select distinct room_category
              from room_category

然后，我建议您将联接该子查询保留到查询的其余部分，并使用它的值对其进行分组。最终看起来会是这样的：

select a.room_category, 
       group_concat(b.room_name ORDER BY b.room_name) vacancies
  from (select distinct id, room_category from room_category) a
  left join 
       (select rct.room_category AS room_category,
               rn.room_name 
          from room_category rct  
          left join room_name rn on rn.room_category = rct.id
          left join patient_detail pd on rn.id = pd.bed_type
                 and (isnull(pd.discharge_date) or now() 
                      between pd.admission_date and pd.discharge_date)
         where isnull(pd.id) 
         order by rct.room_category, rn.room_name
    ) b on a.room_category=b.room_category
group by a.room_category
order by a.room_category