Query to update multiple rows with particular data/string in SQL

update tablename set columnname=REPLACE(tablename.columnname,'string to search','string to replace')

Consider the below table with name 'Employee'

ID	Name
1	sa
2	sa krishna
3	sa kumar
4	sa ganesh

After executing the update statement

update Employee set Name=REPLACE(Employee.Name,'sa','sai')  
then the final result will be

ID	Name
1	sai
2	sai krishna
3	sai kumar
4	sai ganesh