按列重新排列列表

Question

我在表中有一列「SortIndex」，我想添加一個「案例更新」，通過傳入ID和所選擇的新位置來重新排序該表。

SQL Fiddle

DECLARE @T TABLE 
(
    ID int, 
    Name char(1), 
    SortIndex int 
) 

INSERT @T 
SELECT 21, 'A', 1 UNION ALL 
SELECT 23, 'B', 2 UNION ALL 
SELECT 35, 'C', 3 UNION ALL 
SELECT 45, 'D', 4 UNION ALL 
SELECT 55, 'E', 5 

SELECT * FROM @T  

DECLARE @SortIndex int 

/* MOVE A -> 4 */ 

SET @SortIndex = (SELECT SortIndex FROM @T WHERE ID = 23) 

/* 
UPDATE @T 
    SET 
     SortIndex = CASE ... ?? 
*/  

/* MOVE D -> 2 */ 

SELECT * FROM @T 

這可能只用case語句來重建sortindex'es來解決這個問題？

UPDATE

期望的結果

A -> 4 

    Name SortIndex 
    B  1 
    C  2 
    D  3 
    A  4 
    E  5 

    D -> 2 

    A  1 
    D  2 
    B  3 
    C  4 
    E  5 

Answer 1

使用下面的代碼移動和重建索引，它需要的元素後加元和（基於評論澄清答案）進入他人：

這是更苗條的版本：

移動到位置

DECLARE @SortIndex int,@MoveTo int, @CurrentSortIndex int 

SET @CurrentSortIndex = (SELECT SortIndex FROM @T WHERE ID = 45) --D 
SET @MoveTo = 2 

UPDATE--D 
    @T 
SET 
    SortIndex = @MoveTo 
WHERE 
    ID = 45 

UPDATE 
    @T 
SET 
    SortIndex = SortIndex - ((@MoveTo-@CurrentSortIndex)/(ABS(@MoveTo-@CurrentSortIndex))) 
WHERE 
(
    SortIndex BETWEEN @CurrentSortIndex AND @MoveTo 
OR 
    SortIndex BETWEEN @MoveTo AND @CurrentSortIndex 
) 
AND 
    ID != 45 

完整的示例，也sqlfidle鏈接http://sqlfiddle.com/#!3/d41d8/5918：

DECLARE @T TABLE 
(
    ID int, 
    Name char(1), 
    SortIndex int 
) 

INSERT @T 
SELECT 21, 'A', 1 UNION ALL 
SELECT 23, 'B', 2 UNION ALL 
SELECT 35, 'C', 3 UNION ALL 
SELECT 45, 'D', 4 UNION ALL 
SELECT 55, 'E', 5 


DECLARE @SortIndex int,@MoveTo int, @CurrentSortIndex int 
DECLARE @IDToMove INT 
SET @IDToMove = 21--A 

SET @CurrentSortIndex = (SELECT SortIndex FROM @T WHERE ID = @IDToMove) 
SET @MoveTo = 2 

UPDATE 
    @T 
SET 
    SortIndex = @MoveTo 
WHERE 
    ID = @IDToMove 

UPDATE 
    @T 
SET 
    SortIndex = SortIndex - ((@MoveTo-@CurrentSortIndex)/(ABS(@MoveTo-@CurrentSortIndex))) 
WHERE 
(
    SortIndex BETWEEN @CurrentSortIndex AND @MoveTo 
OR 
    SortIndex BETWEEN @MoveTo AND @CurrentSortIndex 
) 
AND 
    ID != @IDToMove 

SELECT * FROM @T ORDER BY SortIndex 

初始版本：

DECLARE @SortIndex int,@MoveTo int, @CurrentSortIndex int 

SET @CurrentSortIndex = (SELECT SortIndex FROM @T WHERE ID = 21) --A 
SET @MoveTo = 2 

UPDATE--A 
    @T 
SET 
    SortIndex = @MoveTo 
WHERE 
    ID = 21 

IF @MoveTo > @CurrentSortIndex 

UPDATE 
    @T 
SET 
    SortIndex = SortIndex - 1 
WHERE 
    SortIndex BETWEEN @CurrentSortIndex AND @MoveTo 
AND 
    ID != 21 

IF @MoveTo < @CurrentSortIndex 

UPDATE 
    @T 
SET 
    SortIndex = SortIndex + 1 
WHERE 
    SortIndex BETWEEN @MoveTo AND @CurrentSortIndex 
AND 
    ID != 21 

Answer 2

UPDATE @T 
SET SortIndex = CASE Name 
     when 'A' then 4 
     when 'D' then 2 
     else Name 
    end