How can I add time to time. 1

[bandarna]

How can I add time to time.

e.g. I want to add 40 mi to sysdate.

select sysdate + 40 from dual;
how can I do this?
Even If convert my date like 20030311000000 forma and add it is going to infinite

select FGNR_EIN,to_Char(d_f2_st50)+50 from orders
where FGNR_EIN = 'LT42355'


FGNR_EI TO_CHAR(D_F2_ST50)+50
------- ---------------------
LT42355 2.003E+13

 

[swampBoogie]

select current_date + interval '40' minute from dual