The usage of trunc function
The usage of TRUNC function
The TRUNC function is used to truncate values.
There are two uses: TRUNC (NUMBER) represents the truncation number, and TRUNC (date) represents the truncation date.
(1) truncation figures:
Format: TRUNC (N1 ~ N2), N1 represents the truncated number, N2 indicates the bit to be truncated. N2 can be a negative number, which means before the truncated decimal point. Note that TRUNC truncation is not rounded.
SQL > select TRUNC (15.79) from dual
TRUNC (15.79)
-
fifteen
SQL > select TRUNC (15.79jue 1) from dual
TRUNC (15.79 and 1)
-
15.7
SQL > select trunc (15.79) from dual
TRUNC (15.79 Mai Mui 1)
-
ten
(2) cut-off date:
Execute the command first: alter session set nls_date_format='yyyy-mm-dd hh34:mi:hh'
Intercept today:
SQL > select sysdate,trunc (sysdate,'dd') from dual
SYSDATE TRUNC (SYSDATE,'DD')
--
2009-03-24 21:31:17 2009-03-24 00:00:00
Intercept the first day of the week:
SQL > select sysdate,trunc (sysdate,'d') from dual
SYSDATE TRUNC (SYSDATE,'D')
--
2009-03-24 21:29:32 2009-03-22 00:00:00
Intercept the first day of the month:
SQL > select sysdate,trunc (sysdate,'mm') from dual
SYSDATE TRUNC (SYSDATE,'MM')
--
2009-03-24 21:30:30 2009-03-01 00:00:00
Intercept the first day of this year:
SQL > select sysdate,trunc (sysdate,'y') from dual
SYSDATE TRUNC (SYSDATE,'Y')
--
2009-03-24 21:31:57 2009-01-01 00:00:00
Intercept to the hour:
SQL > select sysdate,trunc (sysdate,'hh') from dual
SYSDATE TRUNC (SYSDATE,'HH')
--
2009-03-24 21:32:59 2009-03-24 21:00:00
Intercept to minutes:
SQL > select sysdate,trunc (sysdate,'mi') from dual
SYSDATE TRUNC (SYSDATE,'MI')
--
2009-03-24 21:33:32 2009-03-24 21:33:00
Get the first day of last month:
SQL > select TRUNC (add_months (SYSDATE,-1), 'MM') from dual
