if condition in sql server update query

Question

I have a SQL server table in which there are 2 columns that I want to update either of their values according to a flag sent to the stored procedure along with the new value, so

Answer 1

DECLARE @JCnt int=null
SEt @JCnt=(SELECT COUNT( ISNUll(EmpCode,0)) FROM tbl_Employees WHERE EmpCode=1  )

UPDATE #TempCode
SET janCA= CASE WHEN @JCnt>0 THEN (SELECT SUM (ISNUll(Amount,0)) FROM tbl_Salary WHERE Code=1 )ELSE 0 END
WHERE code=1