Oracle Numeric Date function

Numeric Functions

the commonly used functions for handling numeric values are as follows :

No.	Function name	meaning
1	Digital  round ( column  |  numbers [. ])	Returns the value after the data is rounded
2	number  trunc ( column  |  Number [. Decimal place ])	data interception, i.e. not rounding
< P>3	Digital  mod ( columns  |  numbers,   Column  |  digital )	for remainder

Date Function

date has three operation formulas :

Date + number = date ( date after n days)

Date – number = date ( date before n days)

Date – date = number (number of days between dates)

Example 1: Displays the date three weeks ago ( days).

Select sysdate-21 from dual;

Example 2: Displays the date after two weeks ( in days).

Select sysdate+14 from dual;

Example 3: Query the number of days that each employee has been hired.

Select Sysdate-hiredate from EMP; Select Trunc (sysdate-hiredate) from EMP;

Example 4: Query the month and year that each employee has been hired .

Select Trunc (sysdate-hiredate)/30,trunc (sysdate-hiredate)/365 from EMP;

using Angels to achieve year or month calculations must be inaccurate. Oracle provides the following date functions:

No.	Name of function	Meaning
1	Date add_months ( column | date, number of months )	Returns the date after several months of increase
2	Number Months_between ( column | date, column | date )	Returns the number of months between two dates
3	Date last_day ( column | date )	Returns the last day of the month on which the date is
4	Date next_day ( column | date, week X)	Return date in next week, Day of week X

topic 1: the day after 4 months of implementation.

Select Add_months (sysdate,4) from dual;

Topic 2: Query The number of months of employment of EMP all employees so far.

Select Empno,ename,trunc (Months_between (sysdate,hiredate)) from EMP;

Topic 3: Query The last day of the current month .

Select Last_day (sysdate) from dual;

Topic 4: Find out the year of employment for all employees until now.

mode 1: (Date - Date = days)/365--(cannot remove leap year)

Way 2:months_between (sysdate,hiredate)/12

Select Empno,ename,trunc (Trunc (Months_between (sysdate,hiredate))/12) from EMP;

Oracle Numeric Date function