REPLACE searches a string for a regular pattern, replaces it with another string, and returns the modified string.
CHAR | NCHAR | VARCHAR2 | NVARCHAR2
REPLACE(char, search_string [, replacement_string ])
char is the text expression that is searched.
search_string is the text expression to search for.
replacement_string is the text expression that replaces search_string in char.
REPLACE('Nick Nack', 'N', 'Cl') returns the string Click Clack.