T-SQL ：使用 case 语句进行分区

Question

我有以下 table ：

| RoomID | OrderID | Occupancy | Status        |
+--------+---------+-----------+---------------+
| 01     | 101     | Vacant    | inspection    |
| 01     | 102     | Occupied  | Preservation  |
| 01     | 103     | Occupied  | inspection    |
| 01     | 104     | Vacant    | inspection    |
| 02     | 201     | Vacant    | inspection    |
| 02     | 202     | Occupied  | inspection    |
| 02     | 203     | Vacant    | inspection    |
| 03     | 301     | Vacant    | inspection    |
| 03     | 302     | Occupied  | inspection    |
| 03     | 303     | Occupied  | Preservation  |
| 03     | 304     | Occupied  | Preservation  |
| 04     | 401     | Occupied  | inspection    |
| 04     | 402     | Occupied  | inspection    |
| 04     | 403     | Vacant    | Preservation  |
| 04     | 404     | Occupied  | inspection    |

我需要将我的数据拉到 RoomID 级别，其中 Occupancy = 'Occupied' 和 Status = 'Preservation' 在给定的任何实例中RoomID。

结果应如下所示：

| RoomID | Flag    |
+--------+---------+
| 01     | 1       |
| 02     | 0       |
| 03     | 1       |
| 04     | 0       |

我的印象是这很容易，但我现在看不到，提前感谢您的帮助！

Answer 1

您可以使用条件聚合。

select roomid,
count(distinct case when Occupancy = 'Occupied' and Status = 'Preservation' then 1 end) flag
from tablename
group by roomid

Answer 2

您还可以通过 UNION 使用以下查询。

;with cte_1
 AS
( SELECT DISTINCT RoomId
  FROM YourTable
  WHERE Occupancy='Occupied' AND Status='Predervation')
  SELECT RoomId,1 Status
  FROM cte_1
  UNON
  SELECT DISTINCT RoomId,0 Status
   FROM YourTable t
   WHERE NOT EXISTS(SELECT 1 FROM cte_1 c
               WHERE t.RoomId=c.RoomId)

T-SQL ：使用 case 语句进行分区

T-SQL : partitioning using a case statement

sql

tsql

flags

partitioning