Article updated on February 24, 2018

This blog article answers a comment in this blog article: Identify missing values in two columns using excel formula

Question: I need to do exactly the same thing, but with three character alpha codes instead of numbers. Can anyone help?

Answer:

There are 26*26*26 = 17,576 different alpha codes beginning with AAA and ending with ZZZ. Column F contains all 17,576 alpha codes.

The formula in cell D3 compares the values in column B with the values in column F and extracts only those who are missing in column B.

 

 

Array formula in cell D3:

=INDEX($F$3:$F$17578, SMALL(IF(COUNTIF($B$3:$B$11, $F$3:$F$17578)=0, MATCH(ROW($F$3:$F$17578), ROW($F$3:$F$17578)), ""), ROWS($A$1:A1)))

Download excel *.xlsm file

I made all the alpha codes using a UDF, you don't need the UDF to extract missing alpha codes so you can disable macros for this workbook if you like.

Three character alpha code.xlsm

Functions in this article:

COUNTIF(range,criteria)
Counts the number of cells within a range that meet the given condition

IF(logical_test, [value_if_true], [value_if_false])
Checks whether a condition is met, and returns one value if TRUE, and another value if FALSE

ROW(reference) returns the row number of a reference

SMALL(array,k) Returns the k-th smallest row number in this data set.

ROWS(array) returns the number of rows in a reference or an array