Using Actuate BIRT Viewers : Functions and operators : DIFF_WEEK( )
 
DIFF_WEEK( )
Calculates the number of weeks between two date values.
Syntax
DIFF_WEEK(date1, date2)
Arguments
date1
The first date or date expression to use in the calculation.
date2
The second date or date expression to use in the calculation.
Returns
The number of weeks between date1 and date2. The function calculates the difference by subtracting the week number of date1 from the week number of date2. For example, if date1 is 1/3/08 (week 1 of the year), and date2 is 1/7/08 (week 2 of the year), DIFF_WEEK( ) returns 1.
Example
The following example calculates the number of weeks between each value in the askByDate data field and each value in the shipByDate data field:
DIFF_WEEK([askByDate],[shipByDate])
The following example calculates the number of weeks from each value in the orderDate data field to the end of the year:
DIFF_WEEK([orderDate], "1/1/09")