SQL - Clone a record and its descendants - sql

Question

I would like to be able to clone a record and its descendants in the same table. An example of my table would be the following:
Table1
id | parentid | name
---------------------
1 | 0 | 'Food'
2 | 1 | 'Taste'
3 | 1 | 'Price'
4 | 2 | 'Taste Requirements'
The "id" column is the primary key and auto-increments. The 'Food' record (i.e. where id = 1) has two records underneath it called 'Taste' and 'Price'. The 'Taste' record has a record underneath it called 'Taste Requirements'. I would like to be able to clone the 'Food' record so that Table1 would look like the following:
Table1
id | parentid | name
---------------------
1 | 0 | 'Food'
2 | 1 | 'Taste'
3 | 1 | 'Price'
4 | 2 | 'Taste Requirements'
5 | 0 | 'Cookies'
6 | 5 | 'Taste'
7 | 5 | 'Price'
8 | 6 | 'Taste Requirements'
(where 'Cookies' is the name of the new category that I want to create). I am able to select all the descendants of 'Food' using:
with Table1_CTE( id, parentid, name )
as
(
select t.id, t.parentid, t.name from Table1 t
where t.id = 1
union all
select t.id, t.parentid,t. name from Table1 t
inner join Table1_CTE as tc
on t.parentid = tc.id
)
select id, parentid, name from Table1_CTE
and I am able to clone just the 'Food' record (i.e. where id = 1) using:
insert into Table1 ( parentid, name )
select ( parentid, 'Cookies' )
from Table1 where id = 1
but I am having problems trying to combine the two queries to clone the descendants of 'Food'. Also, I am trying to avoid using stored procedures, triggers, curosrs, etc. Is what I am trying to do possible? I have seen some examples on the web but have been unable to apply them to my requirements.

Answer 1

As Martin suggested, you need to enable IDENTITY_INSERT so that you can push your own identity values. You may also need to acquire a table lock to ensure that Max( Id ) returns the correct value.
If object_id('tempdb..#TestData') is not null
Drop Table #TestData
GO
Create Table #TestData
(
Id int not null identity(1,1) Primary Key
, ParentId int not null
, Name varchar(50) not null
)
GO
Set Identity_Insert #TestData On
GO
Insert #TestData( Id, ParentId, Name )
Values( 1,0,'Food' )
, ( 2,1,'Taste' )
, ( 3,1,'Price' )
, ( 4,2,'Taste Requirement' );
With Data As
(
Select Cast(MaxId.Id + 1 As int) As Id
, T.ParentId
, 'Copy Of ' + T.name As Name
, T.Id As OldId
, 0 As OldParentId
From #TestData As T
Cross Join( Select Max( id ) As Id From #TestData ) As MaxId
Where T.Name = 'Food'
Union All
Select Cast(Parent.id + Row_Number() Over( Order By Child.Id ) + 1 As int)
, Parent.Id
, 'Copy of ' + Child.Name
, Child.Id
, Child.ParentId
From Data As Parent
Join #TestData As Child
On Child.ParentId = Parent.OldId
)
Insert #TestData( Id, ParentId, Name )
Select Id, ParentId, Name
From Data
GO
Set Identity_Insert #TestData Off
GO
Results
id | parentid | name
-- | -------- | -----------------
1 | 0 | Food
2 | 1 | Taste
3 | 1 | Price
4 | 2 | Taste Requirement
5 | 0 | Copy Of Food
7 | 5 | Copy of Taste
8 | 5 | Copy of Price
9 | 7 | Copy of Taste Requirement

Answer 2

Assuming your CTE picks a root record and all it's descendents (it didn't seem to when I reproduced using your data above), then you can clone all selected records and insert like this:
with Table1_CTE( id, parentid, name )
as
(
select t.id, t.parentid, t.name from Table1 t
where c.icategoryid = 1
union all
select t.id, t.parentid,t. name from Table1
inner join Table1_CTE as tc
on t.parentid = tc.id
)
insert into dbo.testinsertheirarchy ( parentid, name )
select parentid, name from Table1_CTE