Hierarchical Queries in SQL Server 2005

Question

Way back when I was working in an Oracle shop I took the CONNECT_BY for granted. Now I\'m stuck working with SQL Server 2005 and have some nasty object hierarchies. Specif

Answer 1

Just FYI. SQL Server 2008 supports a new data type Hierarchy ID.

Answer 2

in SQL Server 2005 you can use Common Table Expressions (CTE) for this.

Answer 3

Having used both, I found CONNECT BY is somewhat more flexible and easier to use than CTE's. The question is not dissimilar to one I answered a few weeks ago. See Here for a brief comparison of CONNECT BY and CTE's and Here for an example of a query using CTE's.

Answer 4

To traverse the Depth of the Hierarchy first then the next sibling level, CTE can be used:

declare @tempTable TABLE
(
    ORGUID int,
    ORGNAME nvarchar(100), 
    PARENTORGUID int,
    ORGPATH nvarchar(max)
)

;WITH RECORG(ORGuid, ORGNAME, PARENTORGUID, ORGPATH)
as
(
    select 
        org.UID,
        org.Name,
        org.ParentOrganizationUID,
        dbo.fGetOrganizationBreadcrumbs(org.UID)
    from Organization org
    where org.UID =1

    union all

    select 
        orgRec.UID,
        orgRec.Name,
        orgRec.ParentOrganizationUID,
        dbo.fGetOrganizationBreadcrumbs(orgRec.UID) 
    from Organization orgRec
    inner join RECORG recOrg on orgRec.ParentOrganizationUID = recOrg.ORGuid

)
insert into @tempTable(ORGUID, ORGNAME, PARENTORGUID,ORGPATH)

select ORGUID, ORGNAME, PARENTORGUID,ORGPATH 
from  RECORG rec 

select * 
from @tempTable where ORGUID in(select MIN(tt.ORGUID) 
                                from @tempTable tt 
                                group by tt.PARENTORGUID)

Answer 5

This creates your typical hierarchical table and uses a CTE to select the hierarchy structure and create a path for each item.

CREATE TABLE tblHierarchy (ID int, ParentID int NULL, Name varchar(128));

INSERT INTO tblHierarchy VALUES (1, NULL, '1');
INSERT INTO tblHierarchy VALUES (2, NULL, '2');
INSERT INTO tblHierarchy VALUES (3, NULL, '3');
INSERT INTO tblHierarchy VALUES (4, 1, '1.1');
INSERT INTO tblHierarchy VALUES (5, 1, '1.2');
INSERT INTO tblHierarchy VALUES (6, 4, '1.1.1');

WITH Parent AS
(
    SELECT
        ID,
        ParentID,
        Name AS Path
    FROM
        tblHierarchy
    WHERE
        ParentID IS NULL

    UNION ALL

    SELECT
        TH.ID,
        TH.ParentID,
        CONVERT(varchar(128), Parent.Path + '/' + TH.Name) AS Path
    FROM
        tblHierarchy TH
    INNER JOIN
        Parent
    ON
        Parent.ID = TH.ParentID
)
SELECT * FROM Parent

OUTPUT:

ID  ParentID    Path
1   NULL        1
2   NULL        2
3   NULL        3
4   1       1/1.1
5   1       1/1.2
6   4       1/1.1/1.1.1