Select Stuff('Muthu Babu', 1, 3, 'Mad') Returns
Madhu Babu
Stuff function stuffs the given string at the specified location.
In the above sample Mad is stuffed from 1 to 3 position of Muthu Babu
This makes it to stuff Mad in place of Mut so the result becomes
Madhu Babu.
Similarly
Select Stuff('Muthu Babu', 1, 1, 'Mad') Returns
Maduthu Babu
Hope this helps.