Of all the hundreds of formulas & thousands of features in Excel, INDEX() would rank somewhere in the top 5 for me. It is a versatile, powerful, simple & smart formula. Although it looks plain, it can make huge changes to the way you analyze data, calculate numbers and present them. It is so important that, whenever I teach (live or online), I usually dedicate 25% of teaching time to INDEX().
Today lets get cozy. Lets start a fling (a very long one). Lets do something that will make you smart, happy and relaxed.
Understanding INDEX formula
In simple terms, INDEX formula gives us value or the reference to a value from within a table or range.
While this may sound trivial, once you realize what INDEX can do, you would be madly in love with it.
Few sample uses of INDEX
1. Lets say you are the star fleet commander of planet zorg. And you are looking at a list of your fleet in Excel (even in other planets they use Excel to manage data). And you want to get the name of 8th item in the list.
INDEX to rescue. Write =INDEX(list, 8)
2. Now, you want to know the captain of this 8th ship, which is in 3rd column. You guessed right, again we can use INDEX,
=INDEX(list, 8,3)
Syntax of INDEX formula
INDEX has 2 syntaxes.
1. INDEX(range or table, row number, column number)
This will give you the value or reference from given range at given row & column numbers.
2. INDEX(range, row number, column number, area number)
This will give you the value or reference from specified area at given row & column numbers.
It may be difficult to understand how these work from the syntax definition. Read on and everything will be clear.
7 reasons why INDEX is an awesome companion
Whether you are in planet zorg managing dozens of star fleet or you are in planet earth managing a list of vendors, chances are you are wrestling everyday with data, pleasing a handful of managers (and clients), delivering like a rock star all while having fun. That is why you should partner with INDEX. It can make you look smart, resourceful and fast, without compromising your existing relationship with another human being.
Data used in these examples
For all these examples (except #6), we will use below data. It is in the table named sf.
Reason 1: Get nth item from a list
You already saw this in action. INDEX formula is great for getting nth item from a list of values. You simply write =INDEX(list, n)
Reason 2: Get the value at intersection of given row & column
Again, you saw this example. INDEX formula can take a table (or range) and give you the value at nth row, mth column. Like this =INDEX(table, n, m)
Reason 3: Get entire row or column from a table
For some reason you want to have the entire or column from a table. A good example is you are analyzing star fleet ages and you want to calculate average age of all ships.
You can write =AVERAGE(age column)
or you can also use INDEX to generate the age column for you. Assuming the fleet table is named sf and age is in column 7
write =AVERAGE(INDEX(sf, ,7))
Notice empty value for ROW number. When you pass empty or 0 value to either row or column, INDEX will return entire row or column.
Likewise, if you want an entire row, you can pass either empty or 0 value for column parameter.
Reason 4: Use it to lookup left
By now you know that VLOOKUP() cannot fetch values from columns to left. It does not matter if the person looking up is the star fleet commander.
But INDEX along with MATCH can fix this problem.
Lets say you want to know which ship has maximum capacity.
- First you find what is the maximum capacity =MAX(sf[Capacity (000s tons)])
- Then you find position of of this capacity in all values =MATCH(max_capacity, sf[Capacity (000s tons)],0)
- Now, extract the corresponding ship name =INDEX(sf[Ship Name], max_capacity_position)
Or in one line, the formula becomes
=INDEX(sf[Ship Name], MATCH( MAX(sf[Capacity (000s tons)]), sf[Capacity (000s tons)], 0))
For more tips read using INDEX + MATCH combination
Reason 5: Create dynamic ranges
So far, your reaction to INDEX’s prowess might be ‘meh!’. And that is understandable. You are of course star fleet commander and it is difficult to please you. But don’t break-up with INDEX yet.
You see, the true power of INDEX lies in its nature. While you may think INDEX is returning a value, the reality is, INDEX returns a reference to the cell containing value.
So this means, a formula like =INDEX(list, 8) looks like it is giving 8th value in list.
But it is really giving a reference to 8th cell.
Since the result of INDEX is a reference, we can use INDEX in any place where we need to have a reference.
Sounds confusing?
For example, to sum up a list of values in range A1:A10, we write =SUM(A1:A10)
Now, in that formula, both A1 and A10 are references.
Since INDEX gives a reference, we can replace either (or both) A1 & A10 with INDEX formula and it still works.
so =SUM(A1 : INDEX(A1:A50,10))
will give the same result as =SUM(A1:A10)
Although the INDEX route appears overly complicated, it has other applications.
Example 1: SUM of staff in first x ships
Lets say you want to sum up staff in first ‘x’ ships in the sf table.
Since ‘x’ changes from time to time, you want a dynamic range that starts from first ship and goes up to xth ship.
Assuming ‘x’ value is in cell M1 and first ship’s staff is in cell G3,
=SUM(G3:INDEX(sf[Staff count], M1))
will give the desired result.
Example 2: A named range that refers to all ship names in column A
Many times you do not know how much data you have. Even star fleet commanders are left in dark. Lets say you are building a new ship tracking spreadsheet. Since your fleet is ever growing, you do not want to constantly update all formulas to refer to correct ranges.
For example, the ship names are in column A, from A1 to An. And you want to create a named range that points to all ships so that you can use this name elsewhere.
If you define the lstShips =A1:A10, then after you add 11th ship, you must edit this name. And you hate repetitive work.
One solution is to use OFFSET formula to define the dynamic range,
like =OFFSET(A1, 0,0, COUNTA(A:A),1)
While this works ok, since OFFSET is volatile function, it will recalculate every time something changes in your workbook. Even when someone replaces a bolt on landing gear of USS Enterprise.
This will eventually make your workbook slow.
That is where INDEX comes.
You see, INDEX is a non-volatile function*.
So you can create lstShips that points to,
=A1: INDEX(A:A, COUNTA(A:A))
*Even though INDEX is non-volatile, since we are using it in defining a range reference, Excel recalculates the lstShips every time you open the file. (reference).
Reason 6: Get any 1 range from a list of ranges
INDEX has another powerful use. You can get any one range from many ranges using INDEX.
Since you are a successful, smart & resourceful star fleet commander, you got promoted. Now you manage fleet of several planets.
And you have similar ship detail tables for each planet in a workbook. And you want to calculate average age of any planet’s ships with just one formula.
Again INDEX to rescue.
Assuming you have 3 different tables – planet1, planet2, planet3
and selected planet number is in cell C1,
write =AVERAGE(INDEX((planet1,planet2,planet3),,,C1))
The reference (planet1,planet2,planet3) will point to all data and C1 will tell INDEX which planet’s data to use.
Pretty nifty eh?!?
Reason 7: INDEX can process arrays
INDEX can naturally process arrays of data (without entering CTRL+Shift+Enter).
For example you want to find out how much staff is in the ships whose captain’s name starts with “R”.
write =SUM(INDEX((LEFT(sf[Captain],1)=“r”)*(sf[Staff count]),0))
Although LEFT(sf[Captain],1)=”r” and sf[Staff count] produce arrays, since INDEX can process arrays automatically, the result comes without CTRL+Shift+Enter
Where as if you use SUM alone =SUM((LEFT(sf[Captain],1)=”r”)*(sf[Staff count])) you have to press CTRL+Shift+Enter to get correct results.
Other formulas: SUMPRODUCT & MATCH too can process arrays automatically.
Download Example Workbook & Get close with INDEX
Since you are going to ask, “I want to spend sometime alone with INDEX in my cubicle right now!”, I made an example workbook. It explains all these powerful uses of INDEX. Go ahead and download it.
Get busy with INDEX.
How to use INDEX in Excel – Video
In this video, learn how to use INDEX formula in Excel with many real-world examples. You can also watch it here.
Why do you love INDEX?
I love INDEX(). If we get a dog, I am going to call her INDEX.
Updated on Feb 2024: We did get a dog, but we call her Excel!
That is how much I love the formula. Almost all my dashboards, complex workbooks and anything that seems magical will have a fair dose of INDEX formulas.
What about you? Do you use INDEX formula often? What are the reasons you love it? Please share your tips, usages and ideas on INDEX using comments.
Learn more about INDEX & other such lovely things in Excel
If you are whistling uncontrollably after reading so far, you are in for a real treat. Check out below articles to become awesome.
- INDEX + MATCH Combination
- Introduction to SUMIFS formula
- Dynamic Array formulas in Excel (especially FILTER) is a good alternative to INDEX
- XLOOKUP formula can do much more than INDEX
- More examples of advanced Excel formulas & INDEX
42 Responses to “Prevent Duplicate Data Entry using Cell Validations”
Hi Chandoo, I need you help in the following problem.
I'm trying to get a direccion from a found result. With this dirreccion I will want the before cell value. For example, If result of a find is 38 localized in cell $C$2, I need to get previus value (cell $B$2 ), maybe Andrés.
Do you know some way to do that?
Thank you for you help.
Hi Chandoo
Thanks for this. One thing though: In my pre-2007 version of Excel, the COUNTIF function doesn't recognise a semicolon (;), but requires a comma.
Is the semicolon an Excel 2007 thing?
Jair... I am not sure I understand what you want. what do you mean by Dirreccion?
@Lincoln: I am sorry, often I forget that I am using European version of excel where the delimiter is ; instead of ,. I have corrected the formula now.
Thanks for this nice tip, i used to do a find all after filling every new items which was cumbersome.
Do you know a way to extend this validation search to other tabs/sheets ?
Thanks for you attention. I'm trying to get of value continue from a found value. Let me show a example:
Name Years
John 35
Maria 28
Teresa 32
If I search the max years, the result is 35, but I need that result to be John. Do you know how I can do it?
@Subbu.. you can easily extend the validation to other sheets by pasting the data validations. See the latest article here: http://chandoo.org/wp/2009/10/28/copy-data-validations/
@Jair.. you can use the large() or small() formulas to do this. for eg. =index(A1:A3,large(B1:B3,1)) will get you the name of the person with highest "years". More help here: http://chandoo.org/excel-formulas/large.html
Hi, I don't know if I'm using bad the formula or its performance is diferent for my Office version. Large() formula return the value in the cell, in my example 35. The index() formula use a range, row and column. I'm using the large() as number of row, and it is bad because into the range don't have row 35. This is my perception. What do you think?
Hi, I going to prove, with this solution by JLD http://jldexcelsp.blogspot.com/2008/07/extraer-direccion-de-celda-en-matriz.html
Hello,
I am trying to attempt data validation in Excel Mobile, but the DV tool isnt available. I want to prevent duplicates is all, any advice on acheiving this in Excel Mobile? Thanks..
@Jair... my french aint that good. it starts at "merci" and ends at "beau coup".
Anyhow, you need to merge the large with vlookup to do this. I am not sure if you have solved the problem. Otherwise let me know with details and I can write the formula in comments.
@Chad... I have never used excel mobile, so I have no idea. May be they have not implemented data validations in excel mobile.
Any excel mobile users out there?
Hi Chandoo, the proposed solution by JlD is interesting. He created a macro to get values when the matrix is not one dimensional, how on my problem. This fuction for me.
I would like to share you my work, how can I upload?
@Jair.. sorry for such a delayed reply.. you can upload the files to skydrive and link them here. Or you can email them to me at chandoo.d @ gmail.com and I will upload them somewhere. But it could take forever if you email files to me as I am a bit lazy.
[...] Day 31: Advanced Data Validation Tricks in Excel – Part 2 [...]
Hi,
Can you help me in Microstrategy?
Br,
Moin
really wonderful article. I feel it is implementing Primary Key concept into spreadsheets.
Hi article on data validation. Excel is a very versatile platform to work with and we use it for all kinds of data tabulation. In fact this must have been the most rudimentary data management tools I must have worked with and knowing such tips only adds functuionality to our user experience. Great article. looking forawrd to read more.
Hi Chandoo,
Thanks for such a nice idea.
I tried copy paste the data into the validated area, but the pop-up msg (warning msg) doesn't came. Is it something that we need to update the data manually each time,.
Do we have any option where we can bulk upload the number and it throws a warning message that the data already exits and do we want to continue with this ?
Please do reply me.
Thank you.
Regards,
Vasanth.
It was really useful chandoo...thanks a lot...
Tried this in excel 2010 and it did not work?
Could the newer excel have changed that much?
@Leo
It works fine in Excel 2010
The formula used above =COUNTIF($B$4:$B$11,B4)<=1
only applies to the range B4:B11
Did you adjust the range to your data?
This page helped me accurately to find solution of my question. thanx
we want to prevent duplicate entries in three columns combined, using data validation, i.e. say, column A has first name and Column B has middle name, Column C has last name. the first name can be duplicate, middle name can be duplicate, last name can be duplicate, but not all three at the same time.
I want to prevent duplicate entries in three columns combine, using data validation, i.e. say, column A has first name and Column B has middle name, Column C has last name. the first name can be duplicate, middle name can be duplicate, last name can be duplicate, but not all three at the same time.
Hi, I've tried above validation method to prevent duplicate value from entering into the cells. It's work, when user key in the data into the selected range. However, it's not working when user copy-&-paste the info into the same range.
Please advice. Thanks.
Hi Chandoo,
Does it work in Excel 2007?
Please Reply
thanks chandoo........
it does not work when data is copy pasted...any solution for this??
hi i m shaloo and i want to know in excel if i write duplicate no.then it says or show about we are write duplicate no.
Hi Chandoo
I've tried using this with a Named Range, which is actually a column in a Table as DV wont accept a table reference, and it wont work.
Also tried using Offset to specify the Named Range, but that wont work either.
Is it possible to use Named Ranges with DV?
Thanks
Kris
I have tried the above formula on a table column. The Error box does not pop up, there is only the small ! next to the cell with the duplicate. The column I am working with is formulas that produce a date. Is the reason it doesn't work that the cells contain formulas rather than data?
The formula works but only if I enter data in cell above it. So for example, if I have "123" in B11 it does not allow me to enter "123" in B10, B9, B8, etc. But I can still enter "123" in B12. Please help! 🙂
Great tip.. thanks a lot
I have 21 years of experience working as data entry assistant. I constantly read several blogs to keep myself up-to-date with the advances in data entry profession. I really enjoyed this blog post. From my several years of experience, I agree with you 100% when you say, “ We all know that data validation is a very useful feature in Excel. You can use data validation to create a drop-down list in a cell and limit the values user can enter. ”
Keep blogging. I will come here again.
--data entry assistant
Hi,
This is really very helpful.
Thank you
how can i assign two validation on a single cell
one is for list validation (means the data should be from that range)
second i want to prevent them from repetition
how can i do this ?
P7 to P506 have GR# which are for list
i want to prevent C column to not to repeat and should be from the P column
@Junaid
Can you please post the question in the Chandoo.org Forums
http://forum.chandoo.org/
You have to register to be able to post questions
Please attach a file so that a specific answer can be delivered.
i made an account but there is no option available to post questions ??
where can i ??
@Jubaid
Goto http://forum.chandoo.org/
Goto Ask an Excel Question
Post New thread
Type your question
Attach a file
Please attach a file so that a specific answer can be delivered.
friend can any one tell me the formula
exname location qty
gaurav 1 1
rofan 2 5
sandeep 3 6
gaurav 4 3
rofan 5 4
sandeep 6 8
gaurav 7 9
If this is a data.
if i want a formula by which if i type gaurav then all the location and qty should be shown in a new page.
i had 5,00,000 sku so if i punch one name i can get the entire details
@Gaurav
Can you please post the question at the Chandoo.org Forums
http://forum.chandoo.org/
Please attach a sample file for a quicker more targeted response
IF(ISERROR(INDEX($B$3:$C$9,SMALL(IF($B$3:$B$9=$B$12,ROW($B$3:$B$9)-ROW($C$2)),ROW(A1:C1)),2)),"",INDEX($B$3:$C$9,SMALL(IF($B$3:$B$9=$B$12,ROW($B$3:$B$9)-ROW($C$2)),ROW(A1:C1)),2))
please explain
YOUR COUNTIF FORMULA IS REALLY HELPFUL AND WORKS. I TRIED SEVERAL SITES BUT THEIR FORMULA DOES NOT WORK. ONLY YOU HAVE GIVEN A RIGHT FORMULA!
THANK YOU!!!!!