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 FileMaker Pro Custom Functions

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MergeLists ( _array1 ; _array2 )

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  Average rating: 4.2  (32 votes)
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Michael Rhodes, Allied Data Service

Merge two value lists at twice the speed of similar functions. Requires RemoveEmptyValues custom function.

Sample Input:
MergeLists (
"tom¶dick¶harry" ;
Sample Output:

 Then copy & paste into FileMaker Advanced's Edit Custom Function window.


Good for lists with fewer than 1,000 values in common. Does not remove duplicate values within each list, but does remove duplicate values between both lists. Does not necessarily leave list1 first. If list 2 is shorter, it will be first, because the function picks the smaller list to de-dup which saves processing time.

Note: these functions are not guaranteed or supported by Please contact the individual developer with any questions or problems.

This is my Custom Function and I want to edit it


5 most recent comments | Show all 8 comments

Hi, thanks for this CF.

I presume, that, if both lists are sorted that the resulting list is also sorted. True?

For example:
_array1 = "2011¶2014"
_array2 = "2011¶2012¶2013¶2014"
produces "2011¶2012¶2013¶2014" as output. Fact or coincidence?



Gary, Bonn, Germany
August 18, 2014 10:56pm

Thanks for the function. I found that the function can fail if there are no common values shared between the lists.

In the second Case function, the first test should be:

IsEmpty ( _commonValues ) ; _array1 & ¶ & _array2


Andy Smith, Birmingham, UK
February 09, 2015 7:19am

Thanks, Andy. I updated the function.

Michael R, Colorado Springs
February 10, 2015 6:18pm

Thanks Michael, saved me some time.

Possible bug: If _List1 is less than _List2, then _List = _List1 & Substitute( _List2 ). But then the result = Middle( _List; 2; <etc> ), which would chop of the first char. If _List2 is longer, then the first char is pilcro.

Also, to make is slightly faster when one list is <empty>, put the IsEmpty() tests outside of the Let().

Richard DeShong, Berkeley, CA, US
March 17, 2015 11:46am

Hi Richard, thanks for your input. The reason I personally prefer the IsEmpty command nested within the Let statement, is so I can weed out null lists. The performance hit shouldn't be observable.

Michael R, Colorado Springs
March 17, 2015 11:50am

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