How to compare the contents of 2 columns with Excel?

 How to compare the contents of 2 columns with Excel?

1. Write a VLOOKUP functions

   The VLOOKUP function will help you to find the missing values

2. Use the ISNA function

   This function will help to convert the previous result as a test

3. Write an IF function

   This function will be useful to customize the final result

Logic to Compare 2 columns in ExcelComparing 2 columns in Excel is very easy. To solve this problem, we will use the VLOOKUP function.

The trick in this situation is to test if the VLOOKUP functions will returns N/A or not?

• If the value is missing, the VLOOKUP function will return N/A.
• Then, we will perform a test on the result N/A

Step 1: Write a VLOOKUP function

Let's start by writing a VLOOKUP function to find, or not, an item in the second column.

=VLOOKUP(A1,$D$1:$D$4,1,0)

1. First, we want to find the value in A1 is in the second column
2. Then, we will verify if this value is present in the column $D$1:$D$4 (do not forget the $ to lock the cell references)
3. The third parameter = 1 because we have selected only one column in the second argument.
4. And last parameter = 0 to perform an exact match.
5. Then copy the formula down the column.

The missing value is immediately visible by the #N/A error value. NA means Not Applicable.

But it is not very visually appealing to display #N/A in your workbook 

Step 2: Use the ISNA function to perform a test

The ISNA function returns TRUE or FALSE

• TRUE: when the function VLOOKUP returns #N/A
• FALSE: when the function has matched

So, with this function, instead of returning N/A, we will return TRUE when the lookup failed.

=ISNA(VLOOKUP(A1,$D$1:$D$4,1,0))

Step 3: Finish with the IF function

Displaying TRUE or FALSE in the cells is not user-friendly. This is why we will integrate this test into an IF function to customize the result. We can write the following IF function:

=IF(ISNA(VLOOKUP(A1,$D$1:$D$4,1,0)),"Missing","")

Change the color of the missing values

If you prefer to change the color, you can insert the logical test with ISNA into a custom rule in conditional formatting. Like that, all the missing values will be displayed with a custom color.