SQL trim everything right of char code example

Example: sql server rtrim everything after character

SELECT   [FullName]
	    ,LEFT([FullName], CHARINDEX(',', [FullName]) - 1) AS [Surname]
	    ,REPLACE(SUBSTRING([FullName], CHARINDEX(',', [FullName]), LEN([FullName])), ',', '') AS [FirstName]
FROM    Employee