Oracle SUBSTR InStr Usage

Select Temp.short_pjt the original name,
Temp.fproject_name name after change,
Temp.fflow_person_name the author,
Temp.fcreate_date Date of submission
From (SELECT Head.fsubject,
T.fflow_person_name,
T.fcreate_date,
SUBSTR (Head.fsubject,
InStr (Head.fsubject, ' ~ ', 1) + 1,
Length (Head.fsubject)) SHORT_PJT,
Head.fproject_name
From Cop_cop_task T, cop. Cop_flow_header Head
where 1 = 1
and t.fmodule_sys_sq = head.fmodule_sys_sq
and T.fflow_type_code = ' project_rename ') temp
Group BY TEMP.SHORT_PJT,
Temp.fflow_person_name,
Temp.fcreate_date,
Temp.fproject_name
ORDER BY temp.fcreate_date Desc

Oracle SUBSTR InStr Usage