Proper Comparisons for Dates in Merge Fields

Volker is having a problem comparing dates in a merge field. His database contains a Birthdate field, which (obviously) contains a birth date for each person in the database. As he merges each record, he wants to compare the Birthdate field to a reference date, and then take some action based on the result. The logic he is attempting to use looks like this:

{IF {MERGEFIELD Birthdate} > "02/26/1981" "Under 30" "Over 30"}

The problem is that the comparison doesn't work properly; it doesn't return consistent results. One possible solution is to use a format switch in the merge field, in the following manner:

{IF {MERGEFIELD Birthdate\@"MM/DD/YYYY"} > "02/26/1981" "Under 30" "Over 30"}

This puts the incoming information into a comparable format. The results you get from this approach may depend, however, on characteristics of the data source, independent of Word. You could also try putting the dates into a year-first format, such as the following:

{IF {MERGEFIELD Birthdate\@"YYYY/MM/DD"} > "2011/02/26" "Under 30" "Over 30"}

If the comparison still yields inconsistent results, then the only solution may be to do a mathematical conversion on the date (actually, on both Birthdate and the reference date) so that you have an actual numeric comparison. You can do this by converting the date into a Julian value, which requires a very complex merge field, like the one shown here:

{IF {QUOTE {SET a{=INT((14-{MERGEFIELD BIRTHDATE \@ M})/12)}}
{SET b{={MERGEFIELD BIRTHDATE \@ yyyy}+4800-a}}
{SET c{={MERGEFIELD BIRTHDATE \@ M}+12*a-3}}
{SET d{MERGEFIELD BIRTHDATE \@ d}}
{SET jd{=d+INT((153*c+2)/5)+365*b+INT(b/4)-INT(b/100)+INT(b/400)-32045}}
{jd \#,0}} > 2,443,056 "over 30" "under30"}

Such an approach may look intimidating, but is just the brute-force method necessary for some instances.

WordTips is your source for cost-effective Microsoft Word training. (Microsoft Word is the most popular word processing software in the world.) This tip (356) applies to Microsoft Word 97, 2000, 2002, and 2003. You can find a version of this tip for the ribbon interface of Word (Word 2007 and later) here: Proper Comparisons for Dates in Merge Fields.