Firebird:如何订购列表聚合？

Question

题:

在下面的查询中我想要等效的

GROUP_CONCAT(ctAncestors.ancestor ORDER BY ctAncestors.depth DESC) AS breadcrumbs_id 

在火鸟.

到目前为止我得到了

LIST(ctAncestors.ancestor, ',') AS breadcrumbs_id 

但我无法弄清楚如何在list指令中添加订单.

如何在List聚合中执行订单？

-- http://www.unlimitedtricks.com/sorting-a-subtree-in-a-closure-table-hierarchical-data-structure/

-- DECLARE @__in_rootnodeId AS bigint 
-- SET @__in_rootnodeId = 8 
-- SET @__in_rootnodeId = 1 


SELECT 
     COALESCE(ctDescendants.ancestor, 0) AS parent_id 
    ,ctAncestors.descendant AS child_id 
    ,tClosureItemsTable.COM_Id 
    ,tClosureItemsTable.COM_Text 

--,'ab' as breadcrumbs

--,LIST(ctAncestors.ancestor ORDER BY ctAncestors.depth DESC) AS breadcrumbs_id 
,LIST(ctAncestors.ancestor, ',') AS breadcrumbs_id 
    --,GROUP_CONCAT(ctAncestors.ancestor ORDER BY ctAncestors.depth DESC) AS breadcrumbs_id 
    -- ,GROUP_CONCAT(breadcrumb_data.COM_Text ORDER BY ctAncestors.depth DESC) AS breadcrumbs 
--,GROUP_CONCAT(breadcrumb_data.COM_Text ORDER BY ctAncestors.depth) AS breadcrumbs 
,LIST(breadcrumb_data.COM_Text) AS breadcrumbs 
--,GROUP_CONCAT(breadcrumb_data.COM_Text ORDER BY ctAncestors.depth DESC SEPARATOR '-') AS breadcrumbs2 




/*  
,
    SUBSTRING
    (
        (
            SELECT 
                -- breadcrumb.ancestor AS 'text()'  -- Remove substring for this 
                -- ', ' + CAST(breadcrumb.ancestor AS nvarchar(36)) AS 'text()'
                ', ' + CAST(breadcrumb_data.comment AS nvarchar(36)) AS 'text()'
            FROM T_CommentClosure AS breadcrumb 

            LEFT JOIN Comments AS breadcrumb_data
                ON breadcrumb_data.COM_Id = breadcrumb.ancestor

            WHERE (breadcrumb.descendant = ctAncestors.descendant) 

            ORDER BY breadcrumb.depth DESC
            FOR XML PATH('')
        )
        ,2
        ,8000
    ) AS breadcrumbs 
*/  

    ,
    (
        SELECT COUNT(*) FROM T_CommentClosure AS tp 
        WHERE tp.ancestor = tClosureItemsTable.COM_Id AND tp.depth = 1 
    ) AS ChildCount 

FROM T_CommentClosure AS ctAncestors  

-- Must be left join, for root node
LEFT JOIN T_CommentClosure AS ctDescendants 
    ON (ctDescendants.descendant = ctAncestors.descendant) 
    AND (ctDescendants.depth = 1) 

-- INNER JOIN just in case item has been somehow deleted when FK disabled 
INNER JOIN T_Comments AS tClosureItemsTable  
    ON (ctAncestors.descendant = tClosureItemsTable.COM_Id) 

INNER JOIN T_Comments AS breadcrumb_data
    ON breadcrumb_data.COM_Id = ctAncestors.ancestor 

WHERE (1=1) 
-- AND (ctAncestors.ancestor = @__in_rootnodeId) -- ROOT node id 
AND 
( 
    -- ( ctAncestors.ancestor = @__in_rootnodeId) -- ROOT node id 
    (1=2) 
    OR 
    (1=1)
--    (@__in_rootnodeId IS NULL) 
) 

-- AND tClosureItemsTable.active = 1 

GROUP BY 
     ctAncestors.descendant 
    ,ctDescendants.ancestor 
    ,tClosureItemsTable.COM_Id 
    ,tClosureItemsTable.COM_Text 

ORDER BY breadcrumbs ASC  -- DESC

Answer 1

作为国家的文件LIST():

列表值的排序未定义.

也就是说,如果您使用首先按GROUP BY-columns和此列排序的子查询或公用表表达式(CTE),那么它将起作用,但这确实意味着您依赖于可能随点发布或新更改的实现工件版本.

Firebird跟踪器中有一个改进票据(CORE-2332),但它还没有计划用于版本.此票证还包含解决方法的示例:

WITH EDU_EPT AS (
  SELECT EEPT2.TARGET_SWE
  FROM EDUCATION_EVENT_PR_TRGT EEPT2
  WHERE EEPT2.EDUCATION_EVENT_ID = :EDU_EVENT_ID
  ORDER BY EEPT2.ORDINAL, EEPT2.ID
)
SELECT LIST('• ' || EEPT.TARGET_SWE, ASCII_CHAR(13) || ASCII_CHAR(10)) || '.'
FROM EDU_EPT EEPT