Calculate the difference between two date picker controls in InfoPath using rules and formulas - no code!

REF: http://www.bizsupportonline.net/infopath2007/calculate-date-difference-infopath-rules-formulas.htm


Use rules, conditions, and the number(), floor(), and substring() functions in formulas to calculate the difference between two date picker controls in InfoPath.

Problem
You have an InfoPath form template with two date picker controls and you would like to calculate the difference between the two date picker controls without writing code.

Solution
Use rules, conditions, and the number(), floor(), and substring() functions in formulas to calculate the difference between two date picker controls in InfoPath.

Discussion
You can accomplish this functionality as follows:

Design an InfoPath form template as shown in figure 1 with two Date Picker controls named startDate and endDate, and one Text Box control named difference.

Figure 1. InfoPath form template in Design mode.

The Main data source of the InfoPath form template should resemble the following figure:

Figure 2. The Main data source of the InfoPath form template.
Add the following Rule to the startDate field:
Action: Set a field's value
Field: difference
Value:

(number(substring(../my:endDate, 9, 2)) + floor((153 * (number(substring(../my:endDate, 6, 2)) + 12 * (floor((14 - number(substring(../my:endDate, 6, 2))) div 12)) - 3) + 2) div 5) + (number(substring(../my:endDate, 1, 4)) + 4800 - (floor((14 - number(substring(../my:endDate, 6, 2))) div 12))) * 365 + floor((number(substring(../my:endDate, 1, 4)) + 4800 - (floor((14 - number(substring(../my:endDate, 6, 2))) div 12))) div 4) - floor((number(substring(../my:endDate, 1, 4)) + 4800 - (floor((14 - number(substring(../my:endDate, 6, 2))) div 12))) div 100) + floor((number(substring(../my:endDate, 1, 4)) + 4800 - (floor((14 - number(substring(../my:endDate, 6, 2))) div 12))) div 400) - 32045) - (number(substring(., 9, 2)) + floor((153 * (number(substring(., 6, 2)) + 12 * (floor((14 - number(substring(., 6, 2))) div 12)) - 3) + 2) div 5) + (number(substring(., 1, 4)) + 4800 - (floor((14 - number(substring(., 6, 2))) div 12))) * 365 + floor((number(substring(., 1, 4)) + 4800 - (floor((14 - number(substring(., 6, 2))) div 12))) div 4) - floor((number(substring(., 1, 4)) + 4800 - (floor((14 - number(substring(., 6, 2))) div 12))) div 100) + floor((number(substring(., 1, 4)) + 4800 - (floor((14 - number(substring(., 6, 2))) div 12))) div 400) - 32045)

with the following Conditions on the Rule:
startDate is not blank and
endDate is not blank
Add a second Rule to the startDate field with the following settings:
Action: Set a field's value
Field: difference
Value: 0

with the following Conditions on the Rule:
startDate is blank or
endDate is blank

Add the following Rule to the endDate field:
Action: Set a field's value
Field: difference
Value:

(number(substring(., 9, 2)) + floor((153 * (number(substring(., 6, 2)) + 12 * (floor((14 - number(substring(., 6, 2))) div 12)) - 3) + 2) div 5) + (number(substring(., 1, 4)) + 4800 - (floor((14 - number(substring(., 6, 2))) div 12))) * 365 + floor((number(substring(., 1, 4)) + 4800 - (floor((14 - number(substring(., 6, 2))) div 12))) div 4) - floor((number(substring(., 1, 4)) + 4800 - (floor((14 - number(substring(., 6, 2))) div 12))) div 100) + floor((number(substring(., 1, 4)) + 4800 - (floor((14 - number(substring(., 6, 2))) div 12))) div 400) - 32045) - (number(substring(../my:startDate, 9, 2)) + floor((153 * (number(substring(../my:startDate, 6, 2)) + 12 * (floor((14 - number(substring(../my:startDate, 6, 2))) div 12)) - 3) + 2) div 5) + (number(substring(../my:startDate, 1, 4)) + 4800 - (floor((14 - number(substring(../my:startDate, 6, 2))) div 12))) * 365 + floor((number(substring(../my:startDate, 1, 4)) + 4800 - (floor((14 - number(substring(../my:startDate, 6, 2))) div 12))) div 4) - floor((number(substring(../my:startDate, 1, 4)) + 4800 - (floor((14 - number(substring(../my:startDate, 6, 2))) div 12))) div 100) + floor((number(substring(../my:startDate, 1, 4)) + 4800 - (floor((14 - number(substring(../my:startDate, 6, 2))) div 12))) div 400) - 32045)

with the following Conditions on the Rule:
startDate is not blank and
endDate is not blank
Add a second Rule to the endDate field with the following settings:
Action: Set a field's value
Field: difference
Value: 0

with the following Conditions on the Rule:
startDate is blank or
endDate is blank
Add the following Rule to the difference field:
Action: Set a field's value
Field: .
Value: 0

with the following Condition on the Rule:
difference does not match pattern Custom Pattern: -{0,1}\d+
You should now have a fully functional InfoPath form that will calculate the difference between the dates soon after you have entered valid dates. This solution also works for InfoPath 2003 form templates and InfoPath 2007 browser-enabled form templates.