Hi Naina, Check the Script, U can use CASE Statement in UPDATE.
CREATE TABLE #EmpDtls(ID INT, EmpGender CHAR(1))
INSERT INTO #EmpDtls (ID, EmpGender) VALUES (1,'M'),(2,'F'),(3,'M')
SELECT ID, EmpGender FROM #EmpDtls
-- Update Statement
UPDATE #EmpDtls SET EmpGender = (CASE WHEN EmpGender='M' THEN 'F' WHEN EmpGender='F' THEN 'M' END)
SELECT ID, EmpGender FROM #EmpDtls
Regards, GVPrabu