Correct Oracle TRUNC function usage

I have learned a little about Oracle TRUNC functions. If you want to use trunc (date, ''dd'') in actual operations one day ''). you can open this article for a more comprehensive understanding. The following is a detailed description of the article.

To put it bluntly, the format is year, accurate to ----- year.

For months, accurate to ------ year, month (no matter which year, as long as it is the same month and day)

Is the day, accurate to ------ year, month, day (regardless of which month, only care about the day)

1. TRUNC (for dates)

The date value intercepted by the TRUNC function for the specified element.

The syntax format is as follows:

 
 

  
  
Oracle TRUNCdate[,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:

 
 

  
  
TRUNCTO_DATE(’24-Nov-1999 08:00 pm’,’dd-mon-yyyy hh:mi am’)）  
  
  
=’24-Nov-1999 12:00:00 am’  
  
  
TRUNCTO_DATE(’24-Nov-1999 08:37 pm’,’dd-mon-yyyy hh:mi am’,’hh’)） =’24-Nov-1999 08:00:00 am’  
 
 

When no format is specified for round (date, ''format''), if the time in the date is before noon, the time in the date is truncated to 12. m. (midnight, the beginning of a day), or enter the next day.

If format is not specified for TRUNC (date, ''format''), the date is cut to 12 A. M., and the condition before noon is not considered.

2. TRUNC (for number)

The Oracle 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:

 
 

  
  
TRUNCnumber[,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:

TRUNC89.985, 2) = 89.98

TRUNC89.985) = 89

TRUNC89.985,-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.