The easiest way is probably with VLOOKUP(). This will require the 2nd worksheet to have the employee number column sorted though. In newer versions of Excel, apparently sorting is no longer required.
For example, if you had a "Sheet2" with two columns - A = the employee number, B = the employee's name, and your current worksheet had employee numbers in column D and you want to fill in column E, in cell E2, you would have:
=VLOOKUP($D2, Sheet2!$A$2:$B$65535, 2, FALSE)
Then simply fill this formula down the rest of column D.
Explanation:
- The first argument
$D2 specifies the value to search for.
- The second argument
Sheet2!$A$2:$B$65535 specifies the range of cells to search in. Excel will search for the value in the first column of this range (in this case Sheet2!A2:A65535). Note I am assuming you have a header cell in row 1.
- The third argument
2 specifies a 1-based index of the column to return from within the searched range. The value of 2 will return the second column in the range Sheet2!$A$2:$B$65535, namely the value of the B column.
- The fourth argument
FALSE says to only return exact matches.