Question

I am using T/SQL in SQL Server 2008

I have a table MyTable with the following columns:

 CHILD
 PARENT
 HIERARCHY 

The HIERARCHY column is currently empty, but I would like to populate it.

I have some code which creates a hierarchy ID (adapted from the code in Recursive Child/Parent queries in T/SQL)
This code works very nicely.

with n(CHILD, PARENT, GENERATION, hierarchy) as (
select CHILD, PARENT,0, CAST(CHILD as nvarchar) as GENERATION from MyTable
where PARENT=1 
union all
select nplus1.CHILD, nplus1.PARENT, GENERATION+1, 
cast(n.hierarchy + '/' + CAST(nplus1.CHILD as nvarchar) as  nvarchar)
 from 
MyTable nplus1 inner join n on nplus1.PARENT=n.CHILD and    
)

I can see the results of this query by doing:

select CHILD,GENERATION,Hierarchy from n

However I would like to put the result back in the column Hierarchy in MyTable.
This code does not work!

update MyTable e
set HIERARCHY='/'+(select hierarchy from n where n.CHILD=e.CHILD)

Does anyone know how to do it? Thank you!

Answer 1

Maybe something like this:

;with n(CHILD, PARENT, GENERATION, hierarchy) as (
select CHILD, PARENT,0, CAST(CHILD as nvarchar) as GENERATION from MyTable
where PARENT=1 
union all
select nplus1.CHILD, nplus1.PARENT, GENERATION+1, 
cast(n.hierarchy + '/' + CAST(nplus1.CHILD as nvarchar) as  nvarchar)
 from 
MyTable nplus1 inner join n on nplus1.PARENT=n.CHILD and    
)
UPDATE MyTable 
   SET Hierarchy=n.hierarchy
FROM MyTable 
JOIN n
  ON n.CHILD=MyTable.CHILD

Edit

You mean like this:

;with n(CHILD, PARENT, GENERATION, hierarchy) as (
select CHILD, PARENT,0, CAST(CHILD as nvarchar) as GENERATION from MyTable
where PARENT=1 
union all
select nplus1.CHILD, nplus1.PARENT, GENERATION+1, 
cast(n.hierarchy + '/' + CAST(nplus1.CHILD as nvarchar) as  nvarchar)
 from 
MyTable nplus1 inner join n on nplus1.PARENT=n.CHILD and    
)
UPDATE MyTable 
SET Hierarchy='/'+n.hierarchy+'/' 
FROM MyTable e 
JOIN n ON n.child=e.child