我正在建立一个基于4表的分层菜单。在做研究之后，我能想到的唯一解决方案就是到目前为止我已经接近联盟，但我仍然没有达到预期的效果。
4我正在使用的表是
我必须根据对previous question which is directly related to this question的一些建议对我的数据库进行一些更改，之前的问题包含有关数据库的详细信息。
我需要这些列PID, MENU, Handler,PageLangID, ParentID,IssueID, CatID,MenuPosition
创建我的分层菜单我写了下面的内容，它为我提供了所需的列，但我无法在菜单上运行DISTINCT，因此我只能获得Unique Row，并根据该结果集我可以创建我的菜单。
当我尝试添加DISTINCT (Menu)时，它会生成语法错误。
根据我在previous question提到的要求，我不确定这种方法是否合适，或者我应采取其他方法，这种方法不含糊或更专业
QUERY
SELECT PID, MENU, Handler, PageLangID, ParentID,IssueID, CatID, MenuPosition
FROM (
--Pages Table
SELECT PageId AS PID,SUBSTRING(PageName,0,20) AS MENU,SUBSTRING(PageInternalLinkURL,0,24) AS Handler, PageLangID,PageInheritance AS ParentID, 1 AS IssueID, 1 AS CatID,
PageLinkPosition as MenuPosition FROM pg_Pages WHERE PageLangID = 1
UNION
--Article Table
SELECT p.PageID as PID, SUBSTRING(c.ArticleCategoryName,0,20) AS MENU,SUBSTRING(p.PageInternalLinkURL,0,24) AS Handler,LanguageID,p.PageID AS ParentID,IssueID,c.ArticleCategoryID AS CatID,
1 AS MenuPosition FROM art_Articles a JOIN art_Category c ON a.ArticleCategoryID = c.ArticleCategoryID JOIN pg_pages p ON p.PageID = a.PageID WHERE LanguageID =1
UNION
--Article Category Table
SELECT p.PageID AS PID, SUBSTRING(c.ArticleCategoryName,0,20) AS MENU,SUBSTRING(p.PageInternalLinkURL,0,24) AS Handler, LangID,p.PageID,1, ArticleCategoryID,
1 AS MenuPosition FROM art_Category c JOIN pg_Pages p ON c.PageID = p.PageID WHERE LangID =1
UNION
--Magazine Table
SELECT p.PageID AS PID, CAST(IssueCode AS varchar(10)),SUBSTRING(p.PageInternalLinkURL,0,24) AS Handler,LangID,p.PageID AS ParentID, m.IssueID AS IssueID, 1,
1 AS MenuPosition FROM Magazine m JOIN pg_pages p ON m.PageID = p.PageID WHERE LangID =1
) AS T WHERE T.PageLangID = 1 ORDER BY MenuPosition
输出
PID MENU Handler PageLangID ParentID IssueID CatID MenuPosition
----------- -------------------- ------------------------ ----------- ----------- ----------- ----------- ------------
5 Book Review Articles.aspx 1 5 5 18 1
5 Business Articles.aspx 1 5 5 16 1
5 Group News Articles.aspx 1 5 5 6 1
5 Infrastructure Articles.aspx 1 5 5 17 1
5 Politics Articles.aspx 1 5 1 1 1
5 Politics Articles.aspx 1 5 3 1 1
5 Politics Articles.aspx 1 5 4 1 1
5 Politics Articles.aspx 1 5 5 1 1
6 Book Review Article-Category.aspx 1 6 1 18 1
6 Business Article-Category.aspx 1 6 1 16 1
6 Chairman's Message Article-Category.aspx 1 6 1 9 1
6 Culture Article-Category.aspx 1 6 1 3 1
6 Economy Article-Category.aspx 1 6 1 2 1
6 Editorial Message Article-Category.aspx 1 6 1 8 1
6 Finance Article-Category.aspx 1 6 1 19 1
6 Group News Article-Category.aspx 1 6 1 6 1
6 Habtoor Leighton Gr Article-Category.aspx 1 6 1 5 1
6 Infrastructure Article-Category.aspx 1 6 1 17 1
6 Lifestyle Article-Category.aspx 1 6 1 20 1
6 People Article-Category.aspx 1 6 1 7 1
6 Politics Article-Category.aspx 1 6 1 1 1
6 Sports Article-Category.aspx 1 6 1 4 1
12 102 Default.aspx 1 12 3 1 1
12 103 Default.aspx 1 12 4 1 1
12 106 Default.aspx 1 12 1 1 1
12 109 Default.aspx 1 12 5 1 1
1 Home Default.aspx 1 0 1 1 10
11 Video Videos.aspx 1 10 1 1 10
2 About Us Page.aspx 1 0 1 1 20
5 Articles Articles.aspx 1 0 1 1 20
6 Categories Article-Category.aspx 1 0 1 1 25
3 News News.aspx 1 0 1 1 30
12 Archive Default.aspx 1 0 1 1 40
10 Multimedia Multimedia.aspx 1 0 1 1 60
答案 0 :(得分：0)
您在外部select语句中使用了order by。 由于没有使用distinct语句的顺序，
因此，在子选择中执行DISTINCT，在外部选择中执行ORDER BY。
希望这有助于解决您的问题。
答案 1 :(得分：0)
您需要在所有SELECT语句上使用DISTINCT
SELECT DISTINCT PID, MENU, Handler, PageLangID, ParentID,IssueID, CatID, MenuPosition
...