Oracle Time Processing

-- Query Date language type

Select * from v$nls_parameters;

Select * fromnls_session_parameters

--to_date (NULL) the usage (insert NULL Field ?? )

Select 1, to_date (null) from dual;

-- actual Time 2012-12-04 18:22 The test results are as follows:

--24 Hour display mode --- requires HH24:mi:ss this form

Select to_char (sysdate,' yyyy-mm-dd HH24:mi:ss ') from dual; --mi is the minute 2012-12-04 18:22:06

Select to_char (sysdate,' yyyy-mm-dd HH24:mm:ss ') from dual; --MM will display the month 2012-12-04 18:12:15

--12 Hour system display mode

select to_char ( Span lang= "en-us" xml:lang= "en-US" >sysdate ' yyyy-mm-dd HH:mi:ss ' )  from dual; --mi is minutes    2012-12-04 06:22:58

Select to_char (sysdate,' yyyy-mm-dd HH:mm:ss ') from dual; --MM will display the month 2012-12-04 06:12:21

--2012-12-04 What day of the week? Tuesday

Selectto_char (to_date (' 2012-12-04 ',' Yyyy-mm-dd '),' Day ') from dual;

--2012-12-04 What day of the week? Tuesday (in American language Display)

Selectto_char (to_date (' 2012-12-04 ',' Yyyy-mm-dd '),' Day ',' nls_date_language = American ') from dual;

--2012-12-04 the Month A Month

Selectto_char (to_date (' 2012-12-04 ',' Yyyy-mm-dd '),' MONTH ') from dual;

--2012-12-04 the Month December (in American language Display)

Select to_char (to_date (' 2012-12-04 ',' Yyyy-mm-dd '),' MONTH ',' nls_date_language = American ') fromdual;

Here is the format of the to_date found online:

to_date format (Take time : 2007-11-02 13:45:25 as an example )

Year:

YY two digits two-digit year display value :

YYY three digits three-bit year display value : 007

YYYY four digits four-digit year display value :

Month:

MM number two-bit month display value : One

The Mon abbreviated character set represents the display value : November , if the English version shows the

The month spelled out character set represents the display value : November , if the English version , display November

Day:

DD Number the day of the month displays the value :

DDD Number the day of the year displays the value :

DY abbreviated when in days abbreviated display value : Friday , if the English version , display Fri

Day spelled out when in days full write display value : Friday , if the English version , display Friday

Ddspth spelled out, ordinal twelfth

Hour:

HH-Digits 12-hour binary display value :

Hh24 digits 24-hour binary display value :

Minute:

MI digits 60 binary display value :

Second:

SS-Digits 60 binary display value :

Other

Q Digit Quarterly display value : 4

WW Digit The first few weeks of the year display value :

W Digit The week of the month display value : 1

The time range in the 24-hour format is: 0:00:00-23:59:59 ....

         12-hour format time range:  1:00:00-12:59:59 ....