Complex Lookup Formulas

Eddie has a series of part numbers in the format 123/45678 or 011/00345. He needs to look up the name of the corresponding part number from a different table. This table consists of three columns. The first column contains the portion of the part number before the slash (such as 123 or 011) and the second column contains the portion after the slash (such as 45678 or 00345). The third column contains the name that Eddie want to look up.

Part of the problem Eddie is having is that in the table, the two columns that each contain a portion of the part number are numeric values. Thus the full part number isn't 011 and 00345, but 11 and 345. Eddie is wondering how to put together a lookup formula for the part numbers (123/45678 or 011/00345) to return the proper part name from the table.

To start with, you need to make some changes to the table that contains the part numbers. The first two columns should be formatted as text, not as numbers. This will treat the values in those columns as text, so that when you enter "011" in the first column, it retains the leading zero. If you have already entered the value as 011 before formatting the column as text, it will still be displayed as 11 (without the leading zero). You will need to not only change the format of the column, but also re-enter any part-number fragments that contain leading zeros.

Next you need to make sure that your part number table includes column headers. For this example, make sure the three column headers are Left, Right, and Name. (You can make these headers bold and underlined, which helps set them off from the values in each column.) Then, create names for the individual columns by following these steps:

1. Select the cells in the part number table. Make sure you also select the newly created headers for each column of the table.
2. Click Insert | Name | Define. Excel displays the Create Names dialog box.
3. Make sure that only the Top Row check box is selected.
4. Click OK.

With your part-number table prepared, you are now ready to look up part numbers. In the cells just to the right of your lookup values (123/45678 and 011/00345) you are going to enter an array formula. Assuming that the first part number is in cell A1, you would enter the following array formula in cell B1:

=INDEX(Name,MATCH(A1,Left&"/"&Right,0))

Remember that to denote this as an array formula you enter it by pressing Shift+Ctrl+Enter. The formula then appears in the Formula Bar with {braces} around it. You can copy the formula down to the other cells in column B, as necessary.

The formula works by pulling the value from the Name column of the table when the corresponding Left-column value concatenated with a slash and the Right-column value matches whatever is in cell A1. If there is no match, the formula returns a #N/A error value, otherwise it returns the desired part number.

Note that this approach will work only if you format the first two columns of your part-number table as text and make sure that the various cells contain any leading zeros. If, for some reason, you cannot format the first two columns of the table in this way (perhaps there are too many of them), then you need to change the lookup formula you are using:

=INDEX(Name,MATCH(A1,TEXT(Left,"000")&"/"&TEXT(Right,"00000"),0))

Note that this version of the formula (which should still be entered as an array formula) uses the TEXT function in two places, to convert the values from the Left and Right columns so they have leading zeros.

ExcelTips is your source for cost-effective Microsoft Excel training. This tip (2787) applies to Microsoft Excel 97, 2000, 2002, and 2003.