IBM Cognos User Manual page 374

Date-to-Days-from-1900
Returns the number of days since Jan. 1, 1900 inclusive.The value returned is
negative if the date is before 1900.
Syntax
date-to-days-from-1900 (date_exp | datetime_exp)
Example
date-to-days-from-1900 (1998-03-20)
Returns the result: 35873
Day
Returns a numeric value for the day of the month from 1 to 31, from a date,
datetime value, or interval.
Syntax
day (date_exp | datetime_exp | interval_exp)
Examples
day (2007-03-20)
Returns the result: 20
day (2007-03-20 18:22:00.000)
Returns the result: 20
day (20 00:00:00.000)
Returns the result: 20
Days-to-End-of-Month
Returns the number of days to the last day of the month from a date or datetime
value.
Syntax
days-to-end-of-month (date_exp | datetime_exp)
Example
days-to-end-of-month (2007-03-20)
Returns the result: 11
First-of-Month
Returns the first day of the month from a date or datetime value. The datetime
value is converted from a date_exp value to a date with the same year and month,
but the day is set to one.
Syntax
first-of-month (date_exp | datetime_exp)
Example
first-of-month (2007-03-20)
Returns the result: 03/01/2007 00:00
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