#Overwriting Data from Data Import Tool

Data Import Tool allows importing documents (like customers, Suppliers, Orders, Invoices etc.) from spreadsheet file into ERPNext. The very same tool can also be used for overwrite values in the existing documents.

<div class="well">Overwriting data from Data Import Tool works only for the saved transactions, and not for Submitted ones.</div>

Let's assume there are no. of items for which we need to overwrite Item Group. Following are the steps to go about overwriting Item Groups for existing Items.

####Step 1: Download Template

Template Used for overwriting data will be same as one used for importing new items. Hence, you should first download template from.

`Setup > Data > Import/Export Data'

Since items to be over-written will be already available in the system, while downloading template, click on "Download with data" to get all the existing items in the template.

<img alt="Download Template" class="screenshot" src="{{docs_base_url}}/assets/img/articles/overwrite-1.gif">
	
####Step 2: Prepare Data

In the template, we can only keep rows of the items to be overwritten and delete the rest. 

Enter new value in the Item Group column for an item. Since Item Group is a master in itself, ensure Item Group entered in the spreadsheet file is already added in the Item Group master.

<img alt="Update Values" class="screenshot" src="{{docs_base_url}}/assets/img/articles/overwrite-2.png">

Since we are overwriting only Item Group, only following columns will be mandatory.

1. Column A (since it has main values of template)
1. Name (Column B)
1. Item Group

Columns of other field which won't have any impact can be removed, even if they are mandatory. This is applicable only for overwriting, and not when importing new records.

####Step 3: Browse Template

After updating Item Groups in spreadheet, come back to Data Import Tool in ERPNext. Browser and select the File/template which has data to be overwritten.

<img alt="Browse template" class="screenshot" src="{{docs_base_url}}/assets/img/articles/overwrite-3.gif">

####Step 4: Upload

On clicking Import, Item Group will be over-written.

<img alt="Upload" class="screenshot" src="{{docs_base_url}}/assets/img/articles/overwrite-4.png">

If validation of values fails, then it will indicate row no. of spreadsheet for which validation failed and needs correction. In that case, you should corrected value in that row of spreadsheet, and then import same file again. If validation fails even for one row, none of the records are imported/overwritten.

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