substring in oraclle code example

Example 1: oracle leftmost characters

-- For Oracle only

-- syntax 
SUBSTR(<main-string>,1,<number-of-characters>)

-- example 
SUBSTR('Useless stuff',1,10) -- OUTPUT: Useless st

-- practical example
SELECT SUBSTR('Useless stuff',1,10)
FROM DUAL;

Example 2: oracle right characters

-- For Oracle only

-- syntax 
SUBSTR(<main-string>,-<number-of-characters>)

-- example 
SUBSTR('Useless stuff',-9) -- OUTPUT: ess stuff

-- practical example
SELECT SUBSTR('Useless stuff',-9)
FROM DUAL;