stuff

Deletes "integer_expression2" characters from "string_expression1" starting at "integer_expression1", and inserts "string_expression2" into "string_expression1" at that position. To delete characters without inserting other characters, "string_expression2" should be null and not " ", which indicates a single space.

stuff ( string_expression1 , integer_expression1 ,
 integer_expression2 , string_expression2 )