使用sp

Question

選擇上一行和下一行我想根據當前的id從表中選擇上一行和下一行。我送電流id存儲過程和使用此查詢：

-- previous 
select top 1 id from table where id < @currentId order by id desc 
-- next 
select top 1 id from table where id < @currentId order by id asc 

問題是，當我送currentId這是在表中的最後一個ID，並要選擇下一行。然後是沒有選擇。前一行同樣的問題，當我發送currentId這是第一個id在表

是否有可能解決這個問題在沒有額外的查詢sql？

Answer 1

編輯 - 剛剛意識到你總是希望返回兩行，再工作......

更新代碼：

SELECT * FROM @t WHERE ID = ( select top 1 id 
           from @t 
           where id < 
            case 
             when exists (select id from @t where id < @ID) 
             then @ID 
             else (@ID + 1) 
            end 
           order by id desc 
          ) 

UNION 

SELECT * FROM @t WHERE ID = ( select top 1 id 
           from @t 
           where id > 
            case 
             when exists (select id from @t where id > @ID) 
             then @ID 
             else (@ID - 1) 
            end 
           order by id 
          ) 

原件後下，我才意識到究竟你想要

你真的很接近，你需要UNION運營商和一個小的語法更改爲您的查詢。

SELECT * FROM [table] WHERE ID = (select top 1 id from @t where id < @ID order by id desc) 
UNION 
SELECT * FROM [table] WHERE ID = (select top 1 id from @t where id > @ID order by id) 

當您傳遞它的ID是第一行或最後一行時，將返回1行，否則返回2行。

測試代碼：

DECLARE @t TABLE 
(
    Id int identity, 
    Col varchar(200) 
) 

INSERT INTO @t VALUES('column one') 
INSERT INTO @t VALUES('column two') 
INSERT INTO @t VALUES('column three') 
INSERT INTO @t VALUES('column four') 
INSERT INTO @t VALUES('column five') 

DELETE FROM @t WHERE ID = 3 

DECLARE @Id int 
SET @Id = 3 -- Change this to other values to further test 

SELECT * FROM @t WHERE ID = (select top 1 id from @t where id < @ID order by id desc) 
UNION 
SELECT * FROM @t WHERE ID = (select top 1 id from @t where id > @ID order by id) 

Answer 2

您可以使用嵌套top。您的「下一行」案例。

SELECT TOP 1 * 
FROM (SELECT TOP 2 * 
     FROM YourTable 
     WHERE id >= @currentId 
     ORDER BY id) T 
ORDER BY id DESC 

，併爲 「上一行」

SELECT TOP 1 * 
FROM (SELECT TOP 2 * 
     FROM YourTable 
     WHERE id <= @currentId 
     ORDER BY id DESC) T 
ORDER BY id ASC