how to compare two columns in excel code example

Example 1: check if values in two columns are equal excel

=IF(COUNTIF($B:$B, $A2)=0, "No match in B", "")

Example 2: how to know duplicate in excel in two columns

=INDEX($A$2:$B$14,MATCH("*"&D2&"*",$A$2:$A$14,0),2)