Two lists of data, need results from both lists - possible vlookup

What is in which column(s)?
Will you please attach a SMALL sample Excel workbook (10-20 rows of data is usually enough)? Please don't attach a picture of one (no-one will want to re-type all your stuff before starting).

1. Make sure that your sample data are truly REPRESENTATIVE of your real data. The use of unrepresentative data is very frustrating and can lead to long delays in reaching a solution.

2. Make sure that your desired solution is also shown (mock up the results manually).

3. Make sure that all confidential information is removed first!!

4. Try to avoid using merged cells. They cause lots of problems!

Unfortunately the attachment icon doesn't work at the moment. So, to attach an Excel file you have to do the following: Just before posting, scroll down to Go Advanced and then scroll down to Manage Attachments. Now follow the instructions at the top of that screen.

Re-read it. I get it now.

To return an alphabetically sorted list of sites (in a2, an array formula):

=IFERROR(INDEX(Sheet1!$A$2:$A$10, MATCH(MIN(IF(COUNTIF($A$1:A1, Sheet1!$A$2:$A$10)=0, 1, MAX((COUNTIF(Sheet1!$A$2:$A$10, "<"&Sheet1!$A$2:$A$10)+1)*2))*(COUNTIF(Sheet1!$A$2:$A$10, "<"&Sheet1!$A$2:$A$10)+1)), COUNTIF(Sheet1!$A$2:$A$10, "<"&Sheet1!$A$2:$A$10)+1, 0)),"")

To return tech, in B2, copied across and down, another array formula:
=IFERROR(INDEX(Sheet1!$B:$B,SMALL(IF(Sheet1!$A$2:$A$10=$A2,ROW(Sheet1!$A$2:$A$10)),COLUMNS($B:B))),"")

Array Formulae are a little different from ordinary formulae in that they MUST be confirmed in the FIRST CELL ONLY by pressing CTRL+SHIFT+ENTER to activate the array, not just ENTER. After that, the array can be dragged down as normal, to cover the desired range.

You will know the array is active when you see curly brackets { } - or "curly braces" for those of you in the USA, or "flower brackets" for those of you in India - appear around the outside of your formula. If you do not use CTRL+SHIFT+ENTER you will (almost always) get an error message or an incorrect answer. Press F2 on that cell and try again.

Don't type the curly brackets yourself - it won't work...

If you don't mind them being unsorted:

=IFERROR(INDEX(Sheet1!$A$2:$A$10,MATCH(0,INDEX(COUNTIF($A$1:$A1,Sheet1!$A$2:$A$10),0),0)),"")

This will still be slow, but will be quicker than the forst one. You can always run this, then sort the data and then apply tyhe second formula...

here is your example back again, with the formulae in place.

You MUST have a header row/blank row in sheet2 (where the results are going)

Change the ranges in the formulae to cover the 5000 rows.

First formula... you need to change the INDEX bit to 5639 as well....

Could you upload a SMALL sample of the file that is showing the circular reference error?

Have you still got a circular reference error? Can u=you post a mock-up showing the problem? There's little point in having half a solution....