Use of the Oracle trunc () function

The use of the--oracle trunc () function
/************** Date ********************/
1.select trunc (sysdate) from dual--2013-01-06 today's date is 2013-01-06
2.select trunc (sysdate, ' mm ') from dual--2013-01-01 returns the first day of the month.
3.select trunc (sysdate, ' yy ') from dual--2013-01-01 returns the first day of the year
4.select trunc (sysdate, ' DD ') from dual--2013-01-06 return current month day
5.select trunc (sysdate, ' yyyy ') from dual--2013-01-01 returns the first day of the year
6.select trunc (sysdate, ' d ') from dual--2013-01-06 (Sunday) returns the first day of the current week
7.select trunc (sysdate, ' hh ') from dual--2013-01-06 17:00:00 current time is 17:35
8.select trunc (sysdate, ' mi ') from dual--2013-01-06 17:35:00 trunc () function no seconds accurate
/*************** Digital ********************/
/*
TRUNC (Number,num_digits)
Number requires a 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.select 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

Use of the Oracle trunc () function