How to query a table which has a parent child relation - join

Question

Situation:
I have a table called "word" which contains a word with the associated translations.
| ID | name | lang_id | parent_id |
|----|----------|---------|-----------|
| 1 | screw | 1 | null |
| 2 | schraube | 2 | 1 |
| 3 | vis | 3 | 1 |
So screw is the main word which has no parent. The other data sets have an association to the parent with the parent_id.
What I want:
I need a query which displays the word I searched for and the word which I typed in.
I want to get the datasets 2 and 3, if I query the word "schraube" from german to french.
I want to get the datasets 1 and 3, if I query the word "screw" from english to french.
...
What I tried:
select word.id, word.name, word.lang_id, word.parent_id
from word
left join word w2 on word.parent_id = w2.parent_id
WHERE w2.name = 'screw';
-- and word.lang_id = 2
Unfortunately the result doesn't contain the word I typed. Also this displays all datasets, not only the ones with the specific language.

Answer 1

You can modifiy th below query to get your answer.
DECLARE #FromLanguageId SMALLINT = 2; --german
DECLARE #ToLanguageId SMALLINT = 3; --french
DECLARE #NAME NVARCHAR(300) = 'schraube';
--DECLARE #FromLanguageId SMALLINT = 1; --english
--DECLARE #ToLanguageId SMALLINT = 3; --french
--DECLARE #NAME NVARCHAR(300) = 'screw';
--Get the mathing record
;
WITH ctematch
AS (
--gets the matching record (child or parent)
SELECT match.*
FROM [word] match
WHERE match.NAME LIKE #NAME),
--Join its sibling , parent and childs
ctefamilydata
AS (SELECT *
FROM ctematch match
UNION
--Parent
SELECT parent.*
FROM ctematch match
INNER JOIN [word] parent
ON match.[parent_id] = parent.[id]
UNION
--Child
SELECT child.*
FROM ctematch match
INNER JOIN [word] child
ON child.[parent_id] = match.[id]
UNION
--Siblings
SELECT siblings.*
FROM ctematch match
INNER JOIN [word] siblings
ON match.[parent_id] = siblings.[parent_id])
--Filter and get the data
SELECT *
FROM ctefamilydata Cte
WHERE Cte.[lang_id] = #ToLanguageId
OR Cte.[lang_id] = #FromLanguageId