Common oracle function operations

1: Give the time, for example, "2011-7-23". query the day of the week;

Select to_char (to_date ('1970-7-23 ', 'yyyy-mm-dd'), 'day', 'nls _ DATE_LANGUAGE = American') from dual;

Result: Saturday

Select to_char (to_date ('1970-7-23 ', 'yyyy-mm-dd'), 'day') from dual;

Result: Saturday

2: Query System time;

Select sysdate from dual;

3: round () Rounding, trunc (x, y) truncates the decimal place floor (y)

4: Print Output cyclically:

SQL> set serverout on SQL> begin    2    for i in 1..10 loop    3      dbms_output.put_line(round(dbms_random.value*100));    4    end loop;    5  end;    6  / 

You must enable the server output. Otherwise, no result is displayed.

5: Number of rows before rownum implicit cursor

Select id from xx table where rownum <xx; subquery is required if order by exists.

Select A. id from (select id from B order by name) a where orwnum <xx;

6: query the IP address of a local machine.

Select UTL_INADDR.get_host_address () from dual;

  select UTL_INADDR.get_host_address('www.qq.com') from dual;