This is simply a brute force division, could be done this way

😎

DECLARE @DECIM DECIMAL(18,5) = 125521.12345;

/* Brute force division */

;WITH NX(N) AS (SELECT N FROM (VALUES

(1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) AS X(N))

,NUMBERS(N) AS

(

SELECT CAST(ROW_NUMBER() OVER

(ORDER BY (SELECT NULL)) AS DECIMAL(18,5)) AS N

FROM NX N1,NX N2,NX N3,NX N4,NX N5,NX N6,NX N7

)

SELECT TOP 1

CAST(CAST((@DECIM * NM.N)

+ ((@DECIM % 1) / (1/NM.N)) AS BIGINT) AS VARCHAR(25))

+ '/' + CAST(CAST(NM.N AS INT) AS VARCHAR(25))

FROM NUMBERS NM

WHERE @DECIM % (CAST(1 AS DECIMAL(18,5))/NM.N) = 0;

Results

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

2510424938/20000