Oracle Date Calculation

Oracle queries the month for how many days, the code is as follows:

Select To_number (Add_months (trunc (' 2014-11-4 11:13:53 ', ' yyyy-mm-dd hh24:mi:ss '), ' mm '), 1)-Trunc (' To_date (' 2014-11-4 11:13:53 ', ' yyyy-mm-dd hh24:mi:ss '), ' mm ')) Daycountfrom dual;select to_number (add_months (trunc (to_  Date (To_char (sysdate, ' yyyy-mm-dd hh24:mi:ss '), ' Yyyy-mm-dd hh24:mi:ss '), ' mm '), 1)-Trunc (To_date (To_char (   Sysdate, ' Yyyy-mm-dd hh24:mi:ss '), ' Yyyy-mm-dd hh24:mi:ss '), ' mm ') Dayscount from  dual

Oracle queries the last day of the month with the following code:

Select To_char (Trunc (Add_months (Last_day (Sysdate),-1) + 1), ' yyyy-mm-dd ') "The first day of the Month", To_char (Last_day (sysdate), ' Yyyy-mm-dd ') "Last day of the month" from  dual;

Attached: Oracle Date operation:

--oracle trunc () function usage/************** date ********************/1.select trunc (sysdate) from dual--2011-3-18 Today's date is 2011-3-18 2.select trunc (sysdate, ' mm ') from dual--2011-3-1 returns the first day of the month. 3.select trunc (sysdate, ' yy ') from dual--2011-1-1 returns the first day of the year 4.select trunc (sysdate, ' DD ') from dual--2011-3-18 return Current Month day 5.select trunc (sysdate, ' yyyy ') from dual--2011-1-1 return the first day of the year 6.select trunc (sysdate, ' d ') from dual--2011-3-13 (star Days) returns the first day of the current week 7.select trunc (sysdate, ' hh ') from dual--2011-3-18 14:00:00 current time is 14:41 8.select trunc (sysdate, ' mi ') The From dual--2011-3-18 14:41:00 TRUNC () function does not have a precise/*************** number ********************//* TRUNC (number,num_digits) num The BER requires the number of truncated rounding. The num_digits is used to specify the number of rounding precision. The default value for Num_digits is 0. TRUNC () function is not rounded when truncated/9.select TRUNC (123.458) from dual--123 10.select TRUNC (123.458,0) from dual--123 11.select TRUNC ( 123.458,1) from dual--123.4 12.select trunc (123.458,-1) from dual--120 13.select trunc (123.458,-4) from dual--0 14.sele CT trunc (123.458,4) From dual--123.458 15.select trunc (123) from dual--123 16.select trunc (123,1) from dual--123 17.select trunc (123,-1) From dual--120

Oracle Date Calculation