Hope You are fine and healthy...

'=IFERROR(INDEX($A$2:$A$9;SMALL(IF(COUNTIF($B$2:$B$9;$A$2:$A$9)=1;ROW($A$2:$A$9)-CELL("row";$A$2:$A$9)+1);ROWS($1:1)));"")

IN above function, countif function is used. what, if I use COUNTIF FUNCTION AS "COUNTIF($A$2:$A$9;$B$2:$B$9)=1. I checked entering this changed function of countif but results are not correct. why is this, what is the reason. Moreover, you wrote "=1" at the end of countif, does it mean that the values which are common or in other words equal in both columns which is equivalent to "=1", so "=1" means return true if values in two columns are aequal???? please help. Besides, If you guide me to a link or videos or some easy to understand books downloadable online on "Array Formulas" it would be a great help for me. As For now, I am not proficient in array formulas. I've mentioned my e mail address below.Your reply would really be helpful as always.

Stay healthy

Regards

Asad Iqbal
Asadmir27@gmail.com
Asadmir27@yahoo.com