substring in oracle sql query code example

Example 1: plsql substr

SUBSTR( string, start_position [, length ] )

Example 2: 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;