Insert on a child table and update FK on parent - sql

Question

I have a parent table with the following structure and data:
---------------------------------------------
| Id | TranslationId | Name |
---------------------------------------------
| 1 | NULL | Image1.jpg |
| 2 | NULL | Image7.jpg |
| 3 | NULL | Picture_Test.png |
---------------------------------------------
And the empty child table which holds the translated images:
-------------------------------------------------------------------------
| Id | De | Fr | En |
-------------------------------------------------------------------------
| | | | |
-------------------------------------------------------------------------
Now I'm looking for a single query statement or at least few queries which I can run without any further programming. Doing this job with scripting or programming would be easy but I have often situations where I need this kind of insert / update. And developing each time a small console app is not feasible.
At the end the two tables should look like this:
---------------------------------------------
| Id | TranslationId | Name |
---------------------------------------------
| 1 | 28 | NULL |
| 2 | 29 | NULL |
| 3 | 30 | NULL |
---------------------------------------------
-------------------------------------------------------------------------
| Id | De | Fr | En |
-------------------------------------------------------------------------
| 28 | Image1.jpg | NULL | NULL |
| 29 | Image7.jpg | NULL | NULL |
| 30 | Picture_Test.png | NULL | NULL |
-------------------------------------------------------------------------
Thank you for any advice.

Answer 1

You could do it something like the below :
INSERT INTO Child
(
Id
,De
,Fr
,En
)
OUTPUT Inserted.Id INTO #Temp
SELECT Id
,De
,Fr
,En
FROM #Values --If you are using a table type to insert into the Child table as a set based approach
;WITH CTE
AS
(
SELECT ROW_NUMBER() OVER(ORDER BY Id) AS Rnk
,Id
FROM #Temp
)
,CTE1 AS
(
SELECT ROW_NUMBER() OVER(ORDER BY Id) AS Rnk
,*
FROM Parent
)
UPDATE cte1
SET TranslationId = cte.Id
FROM CTE1 cte1
JOIN CTE cte ON cte.Rnk = cte1.Rnk

Answer 2

Demo, assuming Name is unique in the first table
create table tab1 (
id int identity
,TranslationId int null
,Name nvarchar(max) null
);
insert tab1 (Name)
values
('Image1.jpg')
,('Image7.jpg')
,('Picture_Test.png')
,(null)
create table tab2 (
id int identity (100,1)
,De nvarchar(max) null
,Fr nvarchar(max) null
,En nvarchar(max) null
);
-- Update them
declare #map table(
name nvarchar(max)
,ref int
);
insert tab2 (de)
output inserted.De, inserted.id
into #map(Name, ref)
select Name
from tab1 src
where Name is not null and not exists (select 1 from tab2 t2 where t2.De = src.Name);
update t1 set TranslationId = ref, Name = null
from tab1 t1
join #map m on t1.Name = m.Name;
select * from tab1;
select * from tab2;

Answer 3

I figured out in the meantime how to do it. Applied on the database, the query looks like this:
DECLARE #Temp TABLE (ImageId INT, Id INT)
MERGE INTO Translation USING
(
SELECT Image.Name AS Name, Image.Id AS ImageId
FROM Candidate
INNER JOIN Candidacy ON Candidate.Id = Candidacy.CandidateId
INNER JOIN Election ON Candidacy.ElectionId = Election.Id
INNER JOIN SmartVoteCandidate ON Candidate.Id = SmartVoteCandidate.CandidateId
INNER JOIN Image ON SmartVoteCandidate.SpiderImageId = Image.Id
WHERE Election.Id = 1575) AS temp ON 1 = 0
WHEN NOT MATCHED THEN
INSERT (De)
VALUES (temp.Name)
OUTPUT temp.ImageId, INSERTED.Id
INTO #Temp (ImageId, Id);
UPDATE Image
SET Image.TranslationId = t.Id, Name = NULL
FROM #Temp t
WHERE Image.Id = t.ImageId
The solution is heavily inspired by
Is it possible to for SQL Output clause to return a column not being inserted?
Using a join in a merge statement