SELECT 
A.COLUMN1
....
.
.
.
.
.
A.COLUMN10
B.COLUMN2
FROM 
SCHEMA.TABLE1 A 
LEFT JOIN

(SELECT MIN(COL_ID) as COL_ID_1,COL_DT as COL_DT_1,LTRIM(RTRIM(COL_A_ID)) AS COL_A_ID_1,
COL_AMT AS COL_AMT_1
    FROM SCHEMA.TABLE2 WHERE COL_DT = '9999-12-31' GROUP BY COL_ID,COL_DT, COL_A_ID, COL_AMT) F
ON
A.COL_DT=F.COL_DT_1 and LTRIM(RTRIM(A.COL_T_A_ID))=F.COL_A_ID_1 and -1*DEC(A.COL_AMT,18,2)=F.COL_AMT_1

with ur

WITH TMP AS
(
SELECT 
  MIN(COL_ID) as COL_ID_1,
  COL_DT as COL_DT_1,
  LTRIM(RTRIM(COL_A_ID)) AS COL_A_ID_1,
  COL_AMT AS COL_AMT_1
FROM SCHEMA.TABLE2 
WHERE COL_DT = '9999-12-31' GROUP BY COL_ID,COL_DT, COL_A_ID, COL_AMT) F	
)
SELECT 
A.COLUMN1
....
.
.
.
.
.
A.COLUMN10
B.COLUMN2
FROM 
SCHEMA.TABLE1 A 
LEFT JOIN TMP F ON ( A.COL_DT=F.COL_DT_1 and LTRIM(RTRIM(A.COL_T_A_ID))=F.COL_A_ID_1 and -1*DEC(A.COL_AMT,18,2)=F.COL_AMT_1)
with ur