Formatting of date and number strings in oracle

Select SYSDATE from dual t; -- system date
Select TO_CHAR (SYSDATE, 'yyyy/MM/DD HH24: MI: ss') from dual t; -- format the date
Select TO_DATE ('2014 18:28:20 ', 'yyyy/MM/DD HH24: MI: ss') from dual t; -- format the date
Select sysdate, sysdate-interval '7' MINUTE from dual; -- current time minus 7 minutes
Select sysdate-interval '7' hour from dual; -- current time minus 7 hours
Select sysdate-interval '7' day from dual; -- current time minus 7 days
Select sysdate, sysdate-interval '7' month from dual; -- current time minus July time
Select sysdate, sysdate-interval '7' year from dual; -- current time minus 7 years
Select sysdate, sysdate-8 * interval '7' hour from dual; -- Time interval multiplied by a number
Select to_number ('192. 2') from dual t; -- output 222
Select to_char (10000000000, '$999,999,999, 99') from dual; -- output by format
Select to_char (1000000, 'l99, 999,99') from dual; -- output RMB10, 000,00
Select trunc (to_number ('192. 1000000 '), 3) from dual; -- retain three valid numbers