Hi and welcome to the forum.

Not certain what you are after but this is my first interpretation

😎

USE tempdb;

GO

SET NOCOUNT ON;

IF OBJECT_ID(N'dbo.TBL_SAMPLE_DATA') IS NOT NULL DROP TABLE dbo.TBL_SAMPLE_DATA;

CREATE TABLE dbo.TBL_SAMPLE_DATA

(

ex_ID VARCHAR(12) NOT NULL

,category_ID INT NOT NULL

,ID INT NOT NULL

)

INSERT INTO dbo.TBL_SAMPLE_DATA (ex_ID,category_ID,ID)

VALUES

('BAR105842',203,2)

,('BAR105842',204,3)

,('BAR105842',210,33)

,('BAR105842',230,89)

,('BAR105842',234,133)

,('FLE10311' ,260,736)

,('FLE10311' ,261,737)

,('FLE10311' ,268,1775)

,('FLE10311' ,282,1776)

,('FLE10311' ,298,2755)

,('XGEN1443' ,315,3041)

,('XGEN1443' ,343,6267)

,('XGEN1443' ,342,6268)

,('XGEN1443' ,345,6269)

,('XGEN1443' ,341,6270)

,('XGEN1443' ,380,13168)

,('XGEN1443' ,383,13169)

,('XGEN1443' ,412,19312);

DECLARE @category_ID INT = 204;

SELECT

SD.ex_ID

,SD.category_ID

,SD.ID

FROM dbo.TBL_SAMPLE_DATA SD

WHERE SD.ex_ID =

( SELECT ex_ID

FROM dbo.TBL_SAMPLE_DATA

WHERE category_ID = @category_ID

)

;

Results

ex_ID category_ID ID

------------ ----------- ----

BAR105842 203 2

BAR105842 204 3

BAR105842 210 33

BAR105842 230 89

BAR105842 234 133