The Oracle and PL/SQL TRIM function removes all specified characters either from the beginning or the ending of a string.
The general format is:
TRIM(LEADING|TRAILING|BOTH trim_char FROM trim_source)
Example 1:
SELECT TRIM(' JOHN WILLIAMS ') FROM DUAL;
returns:
JOHN WILLIAMS
Example 2:
SELECT TRIM(BOTH ' ' FROM ' JOHN WILLIAMS ') FROM DUAL;
returns:
JOHN WILLIAMS