关于时间 trunc 函数的使用

关于时间 trunc 函数的使用。


1. trunc 函数

简介：
The TRUNC (date) function returns date with the time portion of the day truncated to the unit specified by the format model fmt. The value returned is always of datatype DATE, even if you specify a different datetime datatype for date. If you omit fmt, then date is truncated to the nearest day. Please refer to "ROUND and TRUNC Date Functions" for the permitted format models to use in fmt.

例子：

The following example truncates a date:

SELECT TRUNC(TO_DATE('27-OCT-92','DD-MON-YY'), 'YEAR')
  "New Year" FROM DUAL;

New Year
---------
01-JAN-92 

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