Oracle time, date type functions and Parameters

Oracle character numeric date conversion  java code  24 hours is shown in the form of HH24     select to_char (sysdate, ' yyyy-mm-dd HH24:mi:ss ') from dual;     select to_date (' 2005-01-01 13:14:20 ', ' yyyy-mm-dd HH24:mi:ss ') from dual;     to_date () function     1. Date format parameter meaning description   d days of the week   day the name of the day, using spaces to fill 9 characters   dd month of the first day of the   ddd year of the day  &N Bsp;dy Day abbreviated name   IW ISO standard year of the week   IYYY ISO standard four-bit year   yyyy four-bit year   yyy,yy,y year last three bits , two-bit, one   hh hour,   hh24 hours by 12 hours, 24 hours   mi minutes   ss seconds   mm Month  &N Bsp The full name of the   month month of the Mon month is   w the first few weeks of the month   WW      1. Date time interval operation    current time minus 7 minutes   select sysdate,sysdate-interval ' 7 ' MINUTE from dual    & nbsp The current time minus 7 hours   select sysdate-interval ' 7 ' hour from dual      current time minus 7 days   select sysdate-interval ' 7 ' date from dual      current time minus July    Select Sysdate,sysdate-interval ' 7 ' month from dual      current time minus 7 years   select Sysdate,sys Date-interval ' 7 ' year from dual      time interval multiplied by a number   select sysdate,sysdate-8 *interval ' 2 ' Hour from dual     2. Date-to-character Operation   select Sysdate,to_char (sysdate, ' Yyyy-mm-dd hh24:mi:ss ') from dual     select Sysdate,to_char (sysdate, ' Yyyy-mm-dd hh:mi:ss ') from dual     select Sysdate,to_char (sysdate, ' YYYY-DDD Hh:mi:ss ') from dual     select Sysdate,to_char (sysdate, ' yyyy-mm iw-d hh:mi:ss ') from dual     3. Character to date operation   select to_date (' 2003-10-17 21:15:37 ', ' yyyy-mm-dd hh24:mi:ss ') from dual      The concrete usage is similar to the to_char above.   4.to_number    convert characters to numbers using the To_number function   to_numBER (char, [' Format '])      numeric format   9 represents a number   0 force display 0   $ Place a $ character  & nbsp L Place a floating local currency symbol   . Display decimal  &nbsp, display the to_date parameter meaning in the thousand indicator     oracle         1. Date format parameter meaning description    d days of the week    day day name, padding to 9 characters with spaces   The day of the  DD month   the day of the  ddd year    dy    IW ISO standard year of the week    IYYY ISO standard four-digit year    YYYY four-bit year    yyy,yy,y year's most Post three-bit, two-bit, one    HH hour, 12-hour meter    HH24 hour, 24-hour meter    mi min    ss sec    MM Month &nbs P  mon    month Month's full name    w week of the month   the first weeks of the  WW year     1. Date and time interval action   when Time minus 7 minutes  select sysdate,sysdate-interval ' 7 ' MINUTE from dual   current time minus 7 hours  select Sysdate-interva L ' 7 ' hour from dual   current time minus 7 days  select sysdate-interval ' 7 ' date from dual   current time minus July  select sy SdAte,sysdate-interval ' 7 ' month from dual   current time minus 7 years  select Sysdate,sysdate-interval ' 7 ' year from dual &N BSP; time interval multiplied by a number  select sysdate,sysdate-8 *interval ' 2 ' hour from dual     2. Date-to-character Operation   sele CT Sysdate,to_char (sysdate, ' Yyyy-mm-dd hh24:mi:ss ') from dual  select Sysdate,to_char (sysdate, ' Yyyy-mm-dd hh:mi: SS ') from dual  select Sysdate,to_char (sysdate, ' yyyy-ddd hh:mi:ss ') from dual  select Sysdate,to_char (sysdate , ' yyyy-mm iw-d hh:mi:ss ') from dual     3. The character-to-date operation   select to_date (' 2003-10-17 21:15:37 ', ' yyyy-mm-dd hh24:mi:ss ') from dual   specific usage is similar to the above To_char.     4. Use of the Trunk/round function   select trunc (sysdate, ' year ') from dual  select trunc (sysdate) from dual  select To_char (Trunc (sysdate, ' YYYY '), ' YYYY ') from dual      5.oracle has a millisecond data type   --Returns the current time, month, day, hour, minute, millisecond, and Nbsp;select To_char (Current_timestamp (5), ' dd-mon-yyyy HH24:MI:SSxFF ') from dual; --returns the second millisecond of the current time, which specifies the precision (max =9) after seconds  select To_char (Current_timestamp (9), ' Mi:ssxff ') from dual;     6. Calculation program run time (MS)   declare  type RC is ref CURSOR;  L_RC RC;  l_dummy All_objects.object_name%type;  l_start number default dbms_utility.get_time;  begin  for I in 1..  loop  open l_rc for   ' select object_name from all_objects ' | |   ' WHERE object_id = ' | | I  fetch L_RC into L_dummy;  close L_RC;  end Loop;  dbms_output.put_line   (Round ((Dbms_utility.get_time-l_start)/100, 2) | |   ' seconds ... ');     end;