oracle right 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 SQL SUBSTR

SUBSTR(string, :START_POS, :SUBSTR_LENGTH);

SELECT SUBSTR('ABCDEFG',3,4) FROM DUAL;
--OUTPUT: CDEF