How to mark duplicate data in two columns in an Excel table

(The original article is from the post, so you can keep a record for future reference.) This is the case. There are two Excel tables with one column of data in each of the two Excel tables, many of the data in these two columns are the same, but the numbers are different and the sorting is different. Is there any way to mark the same data. Note: The two Excel tables are not in the same file and are two separate files. You can copy them to the same file. Please help me ..! Better details, younger brother, dull

Copy the data to the same worksheet. For example, if the data is in column B of column A, enter = countif (A: A, B1) in column C1, and then copy the drop-down formula to the last row of Column B, in column C, if the value is 1, it indicates that a appears once in column A. If the value is 0, it is not repeated.

For specific use, you have to make it according to the actual situation. For example, if column A and column B have more data than Column B, if you want to mark repeated data in column A based on column B, write the formula on the Right of Column B, if you want to mark repeated data in column B based on column A, write the formula on the left of column.

For example:

How to mark duplicate data in two columns in an Excel table