Use of INSTR and SUBSTR Functions

INSTR ---------------------(string to search, search pattern [, start [,occurrence]])

SUBSTR------------------ (original string, begin [,how far])

---------------------Data Till First Space--------------------------


SELECT substr(Name,1,instr(Name,' ',1,1)-1) from hr_operating_units
 
select substr('Oracle welcomes',1,instr('Oracle welcomes',' ',1,1)-1) from dual;

select substr('Oracle welcomes you',1,instr('Oracle welcomes you',' ',1,2)-1) from dual;------------------Data Till Second Sapce