假设我有两张桌子,“花园”和“鲜花”.这些桌子之间有1:n关系,因为在花园里可以有很多花.是否可以编写一个SQL查询,该查询返回具有以下结构的结果:
GardenName Flower1Name Flower2Name .... (as long as there are entries in flowers) myGarden rose tulip
解决方法
CREATE TABLE #Garden (Id INT,Name VARCHAR(20)) INSERT INTO #Garden SELECT 1,'myGarden' UNION ALL SELECT 2,'yourGarden' CREATE TABLE #Flowers (GardenId INT,Flower VARCHAR(20)) INSERT INTO #Flowers SELECT 1,'rose' UNION ALL SELECT 1,'tulip' UNION ALL SELECT 2,'thistle' DECLARE @ColList nvarchar(max) SELECT @ColList = ISNULL(@ColList + ',','') + QUOTENAME('Flower' + CAST(ROW_NUMBER() OVER (ORDER BY (SELECT 0)) AS VARCHAR)) FROM #Flowers WHERE GardenId = ( SELECT TOP 1 GardenId FROM #Flowers ORDER BY COUNT(*) OVER (PARTITION BY GardenId) DESC ) EXEC (N' ;WITH cte As ( SELECT *,''Flower'' + CAST(ROW_NUMBER() OVER (PARTITION BY GardenId ORDER BY (SELECT 0)) AS VARCHAR) RN FROM #Flowers F ) SELECT Name,' + @ColList + N' FROM cte JOIN #Garden g ON g.Id = GardenId PIVOT (MAX(Flower) FOR RN IN (' + @ColList + N')) Pvt') DROP TABLE #Garden DROP TABLE #Flowers
返回
Name Flower1 Flower2 -------------------- -------------------- -------------------- myGarden rose tulip yourGarden thistle NULL
原文地址:https://www.jb51.cc/mssql/83419.html
版权声明:本文内容由互联网用户自发贡献,该文观点与技术仅代表作者本人。本站仅提供信息存储空间服务,不拥有所有权,不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容, 请发送邮件至 dio@foxmail.com 举报,一经查实,本站将立刻删除。