Question

我有一个带有重复任务的SQL表。例如：

+------------------+----+--------------+
|       Task       | ID | RecurranceID |
+------------------+----+--------------+
| Take Out Garbage |  1 |            0 |
| Order Pizza      |  2 |            0 |
| Eat Breakfast    |  3 |            1 |
| Eat Breakfast    |  4 |            1 |
| Eat Breakfast    |  5 |            1 |
| Order Pizza      |  6 |            0 |
+------------------+----+--------------+

RecurranceID为0的任何内容都不是重复性任务，但是否则是一项重复性任务。

如何在定期任务中显示限制为一行的所有任务？

我希望结果集显示：

+------------------+----+
|       Task       | ID |
+------------------+----+
| Take Out Garbage |  1 |
| Order Pizza      |  2 |
| Eat Breakfast    |  3 |
| Order Pizza      |  6 |
+------------------+----+

使用SQL Server 2012

谢谢！

Answer 1

;WITH MyCTE AS
(
    SELECT Task,
           ID,
           ROW_NUMBER() OVER (PARTITION BY TASK ORDER BY ID) AS rn
    FROM   Tasks
)
SELECT  *
FROM    MyCTE 
WHERE   rn = 1

您的示例数据不清楚，但您可能还需要在RecurranceID子句中应用PARTITION BY，如下所示：

;WITH MyCTE AS
(
    SELECT Task,
           ID,
           RecurranceID,
           ROW_NUMBER() OVER (PARTITION BY TASK,RecurranceID  ORDER BY ID) AS rn
    FROM   Tasks
)
SELECT  *
FROM    MyCTE 
WHERE   rn = 1
                OR RecurranceID = 0

Answer 2

您似乎希望返回所有非重复性任务，以及每个周期性任务的单行（无论它是否与非重复性任务共享名称）。你在寻找：

SELECT Task, ID
FROM RecurringTaskTable
WHERE RecurrenceID = 0

UNION ALL

SELECT Task, MIN(ID) AS ID
FROM RecurringTaskTable
WHERE RecurrenceID <> 0
GROUP BY Task

Answer 3

试试这个：

select distinct task
     , DENSE_RANK () OVER (order by  task) dr
  from tasks

Answer 4

希望这有助于，

DECLARE  @test TABLE(Task VARCHAR(30),
                 ID INT,
                 RecurranceID INT)

INSERT INTO @test
VALUES('Take Out Garbage', '1', '0'),
     ('Order Pizza', '2', '0'),
     ('Eat Breakfast', '3', '1'),
     ('Eat Breakfast', '4', '1'),
     ('Eat Breakfast', '5', '1'),
     ('Order Pizza', '6', '0')


;WITH cte_OneofEach AS
(
   SELECT *,
         ROW_NUMBER() OVER (PARTITION BY Task ORDER BY ID DESC) AS rn
   FROM @test
   WHERE RecurranceID = '1'
)
SELECT Task,ID,RecurranceID
FROM @test
WHERE RecurranceID = '0'
UNION
SELECT Task,ID,RecurranceID
FROM cte_OneofEach
WHERE rn = 1

如何通过重复限制SQL结果

4 个答案: