rnkdate — convert a date value to the first day of the month


date rnkdate ( dateval);  
date dateval ;
timestamp rnkdate ( dateval);  
timestamp dateval ;



A date or timestamp value.


A function which returns a date that is the first day of the month of a given date value.

This function is similar to the date_trunc('month', date) function, but takes care of data type conversions and handles time zones. The postgresql date_trunc() function expects a timestamp or timestamptz data type as input. This can lead to confusion involving time zones.


Always use the rnkdate() function when comparing a date with a RANKS.Rnkdate value. Unless care is taken, use of the Postgresql date_trunc() function can lead to mis-matches due to time zone complications.

While it may well be possible to use the date_trunc() function in place of the rnkdate() function; the possibility of complications due to time zone issues has not been thoroughly investigated. Better safe than sorry.

Page generated: 2023-11-28T17:36:08-05:00.