ORACLE simple functions (TWO)

ORACLE simple function (TWO) 1) date function: 1) sysdate function: This function uses the time zone of the database and returns the date value: eg:

[SQL] SYS @ orcl # select sysdate from dual; SYSDATE -------------- 08-4 month-13 SYS @ orcl #2) months_between () function this function returns two date months with a time difference. Eg: [SQL] SYS @ orcl # select months_between (to_date ('2017-02-03 ', 'yyyy-mm-dd'), to_date ('2017-02-03 ', 2 'yyyy-mm-dd') from dual; MONTHS_BETWEEN (TO_DATE ('2017-02-03 ', 'yyyy-MM-DD'), TO_DATE ('2017-02-03 ', 'yyyy-MM-Example-12 SYS @ orcl # select months_between (to_date ('2017-02-03 ', 'yyyy-mm-dd'), to_date ('2017-02-03 ', 2 'yyyy-mm-dd') month S_between from dual; MONTHS_BETWEEN -------------- 12 3) add_months () function this function adds a month after the specified x month and obtains a date value. Eg: [SQL] SYS @ orcl # select add_months (to_date ('2017-02-03 ', 'yyyy-mm-dd'), 2) add_months from dual; ADD_MONTHS -------------- month-12 SYS @ orcl # select add_months (to_date ('2017-02-03 ', 'yyyy-mm-dd'),-2) add_months from dual; ADD_MONTHS -------------- month 03-12-11 SYS @ orcl #4) next_day () function this function indicates the time value for the first occurrence of day y in a week after the date in x: eg: [SQL] SYS @ orcl # select next_day (to_date ('2017-04-08 ', 'yyyy-mm-dd'), 2) next_day from dual; NEXT_DAY -------------- 15-4 month-13 SYS @ orcl #5) last_day () function this function returns the date of the last day of the month that contains the date parameter x: eg: [SQL] SYS @ orcl # select last_day (to_date ('2017-04-08 ', 'yyyy-mm-dd') last_day from dual; LAST_DAY ------------ 30-4 month-13 SYS @ orcl #6) round () function this function is used to round x. By default, x is the last day, if another date is specified later, such as yyyy, the first day of the last year, for example, [SQL] SYS @ orcl # select round (to_date ('2017-04-08 ', 'yyyy-mm-dd') round from dual; ROUND -------------- month 08-4-13 SYS @ orcl # select round (to_date ('2017-04-08 12:23:23 ', 'yyyy-mm-dd hh24: mi: ss') round from dual; ROUND -------------- month 09-4-13 SYS @ orcl # select round (to_date ('2017-04-08 ', 'yyyy-mm-dd'), 'yyyy') from dual; ROUND (TO_DATE (------------ 01-1 month-13 SYS @ orcl #7) trunc () the function is used for the phase of x date. By default, the start time of the day is truncated. You can specify y at the end, and you can cut off the first day of the year, the first day of the month. For example: [SQL] SYS @ orcl # select trunc (to_date ('2017-04-08 23:23:12 ', 'yyyy-mm-dd hh24: mi: ss') trunc from dual; TRUNC -------------- month-13 SYS @ orcl # select trunc (to_date ('2017-04-08 ', 'yyyy-mm-dd'), 'mm') trunc from dual; TRUNC -------------- month 01-4-13 SYS @ orcl #