Friday, April 29, 2011

Recursive Query To Find All Child Node in SQL server 2005+

How to find the all child of particular parent using the Recursive Query
--here we are creating the table variable so that we can insert some dummy record
Declare @Table Table
(
 TId int,
 ParentId int,
 Name varchar(10)
)
--inserting some records
--using the union all to insert more than one records
insert into @Table
Select 1,NULL,'ICT'
Union All
Select 2,1,'ICT-M1'
Union All
Select 4,1,'ICT-M2'
Union All
Select 7,2,'ICT-M1U1'
Union All
Select 8,2,'ICT-M1U2'
Union All
Select 9,4,'ICT-M2U1'
Union All
Select 10,4,'ICT-M2U2'
Union All
Select 11,7,'ICT-M1U1P1'
Union All
Select 12,7,'ICT-M1U1P2'
Union All
Select 13,8,'ICT-M1U2P1'
Union All
Select 14,8,'ICT-M1U2P2'
Union All
Select 15,9,'ICT-M2U1P1'
Union All
Select 16,9,'ICT-M2U1P2'
Union All
Select 17,10,'ICT-M2U2P1'
Union All
Select 18,10,'ICT-M2U2P2'

--variable to hold data
Declare @ChildNode varchar(1000)
Set @ChildNode='';

 
--use the standard recursive query
;with [CTE] as 
(
 --anchor query where we are finding the all parents
    select TId,ParentId,Name,CAST(ISNULL(CAST(ParentId as varchar(10)),'0') As Varchar(100)) As ChildNode
    from @Table c where c.[ParentId] is null

    union all

 --recursive query where we are finding the all child according to anchor query parent
    select c.TId,c.ParentId,c.Name,
    CAST( p.ChildNode +','+cast(c.TId as varchar(10) ) As Varchar(100)) As ChildNode
    from [CTE] p, @Table c where c.[ParentId] = p.[TId]    
)
--select the child node as per the id
--Assigin the all Ids into  one variable
select @ChildNode=@ChildNode+','+Cast(TId as varchar(10))
from [CTE]
Cross Apply
dbo.Split(ChildNode,',')
where items=9
order by TId

select SUBSTRING(@ChildNode,2,LEN(@ChildNode))

--outpu
--2,7,8,11,12,13,14


----
--create the tabular function to split the multi valued into table
Create FUNCTION [dbo].[Split](@String varchar(8000), @Delimiter char(1))     
returns @temptable TABLE (items varchar(8000))     
as     
begin     
 declare @idx int     
 declare @slice varchar(8000)     
    
 select @idx = 1     
  if len(@String)<1 or @String is null  return     
    
 while @idx!= 0     
 begin     
  set @idx = charindex(@Delimiter,@String)     
  if @idx!=0     
   set @slice = left(@String,@idx - 1)     
  else     
   set @slice = @String     
  
  if(len(@slice)>0)
   insert into @temptable(Items) values(@slice)     

  set @String = right(@String,len(@String) - @idx)     
  if len(@String) = 0 break     
 end 
return     
end


--
Happy Coding

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