ORACLE - String Functions : rtrim

the rtrim function removes all specified characters from the right-hand side of a string.

The syntax is:

rtrim( string1, [ trim_string ] )

string1 is the string to trim the characters from the right-hand side.
trim_string is the string that will be removed from the right-hand side of string1. If this parameter is omitted, the rtrim function will remove all trailing spaces from string1.

For example:

rtrim('hola '); would return 'hola'
rtrim('hola ', ' '); would return 'hola'
rtrim('paris000', '0'); would return 'paris'

rtrim('332312paris1233213', '123'); would return '332312paris' (removes the individual occurrences of '1', '2', and '3')

ORACLE - String Functions : length

The length function returns the length of the specified string.

The syntax is:

length( string )

string is the string to return the length for.
If string1 is NULL, then the function returns NULL.

For example:

length('Hola Mundo') would return 10.
length('') would return NULL.