Oracle trunc () function usage

The trunc () function is composed of two types:

1. trunc (for dates)
The date value intercepted by the trunc function for the specified element.
The syntax format is as follows:
Trunc (date [, FMT])
Where:
Date: A date value.
FMT date format, which is truncated by the specified Element format. Ignore it and it is intercepted by the latest date.
The usage of this function is as follows:
Trunc (to_date ('24-Nov-1999 PM ', 'dd-mon-yyyy hh: Mi am '))
= '24-Nov-1999 12:00:00 am'
Trunc (to_date ('24-Nov-1999 08:00:00 PM ', 'dd-mon-yyyy hh: Mi am', 'hh') = '24-Nov-1999 am'

2. trunc (for number)
The trunc function returns the processed value. Its working mechanism is very similar to that of the round function, except that the function does not round or select the part before or after the specified decimal number.
The syntax format is as follows:
Trunc (number [, decimals])
Where:
Number the value to be intercepted
Decimals indicates the number of digits after the decimal point to be retained. Optional. If this parameter is ignored, all decimal parts are truncated.
The usage of this function is as follows:
Trunc (89.985, 2) = 89.98
Trunc (89.985) = 89
Trunc (89.985,-1) = 80
Note: The second parameter can be a negative number, indicating that the part after the specified number of digits on the left of the decimal point is truncated.