SQL Update a table column with a sequence of values - sql

Question

I have a situation where I am required to create a copy of the data of one table within itself with a different range of foreign key in one of the columns. For example:
--------------------------------------------------------------
|TYPES |ITEMS |SUBITEMS |
|--------------|----------------------|----------------------|
| ID | VALUE | ID | VALUE | TYPEID | ID | VALUE | ITEMID |
|----|---------|----|--------|--------|----|--------|--------|
| 1 | TYPE1 | 1 | ITEMA | 1 | 1 | SUB1 | 1 |
| 2 | TYPE2 | 2 | ITEMB | 1 | 2 | SUB2 | 2 |
| | | 3 | ITEMC | 1 | 3 | SUB3 | 3 |
| | | 4 | ITEMD | 2 | | | |
| | | 5 | ITEME | 2 | | | |
| | | 6 | ITEMF | 2 | | | |
--------------------------------------------------------------
Here I have to copy from SUBITEMS and insert back but with ITEMIDs that have TYPEID as 2 resulting in the following example:
--------------------------------------------------------------
|TYPES |ITEMS |SUBITEMS |
|--------------|----------------------|----------------------|
| ID | VALUE | ID | VALUE | TYPEID | ID | VALUE | ITEMID |
|----|---------|----|--------|--------|----|--------|--------|
| 1 | TYPE1 | 1 | ITEMA | 1 | 1 | SUB1 | 1 |
| 2 | TYPE2 | 2 | ITEMB | 1 | 2 | SUB2 | 2 |
| | | 3 | ITEMC | 1 | 3 | SUB3 | 3 |
| | | 4 | ITEMD | 2 | 4 | SUB1 | 4 |
| | | 5 | ITEME | 2 | 5 | SUB2 | 5 |
| | | 6 | ITEMF | 2 | 6 | SUB3 | 6 |
--------------------------------------------------------------
EDIT 2: If the amount of rows differ in either of the tables (4 Items while 3 SubItems or 3 Items while 4 SubItems) then only those rows should be considered that are enough for a 1:1 relation between the two tables (3 result since that is the least count among either) as shown in the following example.
--------------------------------------------------------------
|TYPES |ITEMS |SUBITEMS |
|--------------|----------------------|----------------------|
| ID | VALUE | ID | VALUE | TYPEID | ID | VALUE | ITEMID |
|----|---------|----|--------|--------|----|--------|--------|
| 1 | TYPE1 | 1 | ITEMA | 1 | 1 | SUB1 | 1 |
| 2 | TYPE2 | 2 | ITEMB | 1 | 2 | SUB2 | 2 |
| | | 3 | ITEMC | 1 | 3 | SUB3 | 3 |
| | | 4 | ITEMD | 2 | 4 | SUB1 | 4 |
| | | 5 | ITEME | 2 | 5 | SUB2 | 5 |
| | | 6 | ITEMF | 2 | 6 | SUB3 | 6 |
| | | 7 | ITEMG | 2 | | | |
--------------------------------------------------------------
Of course the actual data isn't as simple and has many other types and items n subitems and the required IDs would be missing some sequence like 10001, 10008, 40042, etc with many other columns all defining what data is being copied and which IDs need to be thrown over them. It's just the matter of how each data row obtained should get mapped 1:1 to each ID obtained (assuming both as if in their own temp tables before the moment of this merger). Following is a sample of what I am able to do so far:
CREATE TABLE #SubItemsTemp (Value VARCHAR(100))
CREATE TABLE #ItemIDsTemp (TypeID INT)
INSERT INTO #SubItemsTemp (Value)
SELECT
SI.Value
FROM
SubItems SI
JOIN Items IT ON SI.ItemID = IT.ID
WHERE
IT.TypeID = 1
INSERT INTO #ItemIDsTemp(Value)
SELECT IT.ID
FROM Items IT
WHERE IT.TypeID = 2
--What next?
EDIT 1: Forgot to mention the actual question line... How to insert them together into the SUBITEMS table such that the second example comes to fruition?
Footnote: This is a extreme simplification of the actual queries that have several joins to get to "TYPE"

Answer 1

Try this query. Query assumes that ID column in SUBITEMS table is identity and will work only with TypeId's 1 and 2
declare #TYPES table(ID int, VALUE varchar(100))
declare #ITEMS table(ID int, VALUE varchar(100), TYPEID int)
declare #SUBITEMS table(ID int identity(1,1), VALUE varchar(100), ITEMID int)
insert into #TYPES values (1, 'TYPE1'), (2, 'TYPE2')
insert into #ITEMS values (1, 'ITEMA', 1), (2, 'ITEMB', 1), (3, 'ITEMC', 1), (4, 'ITEMD', 2), (5, 'ITEME', 2), (6, 'ITEMF', 2), (7, 'ITEMG', 2)
insert into #SUBITEMS values ('SUB1', 1), ('SUB2', 2), ('SUB3', 3)
; with cte_1 as (
select
s.VALUE, rn = row_number() over (order by i.ID)
from
#ITEMS i
join #SUBITEMS s on s.ITEMID = i.ID
where
i.TYPEID = 1
)
, cte_2 as (
select
ID, rn = row_number() over (order by ID)
from
#ITEMS
where
TYPEID = 2
)
insert into #SUBITEMS
select
a.VALUE, b.ID
from
cte_1 a
join cte_2 b on a.rn = b.rn
select * from #SUBITEMS
Output
ID Value ItemId
------------------
1 SUB1 1
2 SUB2 2
3 SUB3 3
4 SUB1 4
5 SUB2 5
6 SUB3 6