Moving Excel data into an app, step by step

Your app is ready to try. How do you move customers, orders and histories without losing track? A method built around a backup, a small trial and checking the results.

Migrating data means moving information from your Excel file into the new app. The goal is simple: find the right customers, orders and amounts. To get there, start with a copy and a few records you know well.

Keep the original safe

Before cleaning anything, keep a dated copy of the original file somewhere safe. Check that you can open it. Work on another clearly named copy so you can recover information changed by mistake.

Use fictional data for the first exchanges with an AI assistant. Do not send a file containing your customers without understanding where it will be processed. Your data explains how Maestro works.

Prepare the columns and rules

Look for duplicate customers, dates written in different formats and amounts mixing prices with and without tax. Ask someone familiar with the history to review uncertain cases. Do not merge two customers simply because they share a name.

Then write down what formulas and colours mean. For example: a red cell means an invoice needs a reminder. These rules belong in the requirements document, because copying values does not automatically recreate calculations or working habits.

An example of matching columns to fields

In this fictional example, “Customer no.” contains 0018 and becomes “Customer reference” in the app. “Customer” contains Atelier Lune and becomes “Customer name”. Keep 0018 as text if the zeros are part of the reference: this number identifies the customer; it is not a quantity to calculate with.

For each column, write down the destination field, a fictional value, the expected format and what to do if the cell is empty. Clarify dates too: 08/09/2026 means 8 September here. The Excel import preparation sheet includes a worked example and a template to fill in with the person preparing the transfer.

Microsoft explains data cleaning and format choices in its guide to moving Excel data into Access. That guide concerns Access: check the formats your own app actually accepts before preparing the file.

Try a small transfer and count what arrives

Check that the app has an import function; if it does not, plan to have one built. Choose an accepted format, such as Excel or CSV, then match each column to its field: “Customer” to “customer name”. First run this import in a test version, using a copy of a few rows.

Take a fictional example: you try to transfer 20 orders. The report shows 18 imported orders and 2 rejected because their customer is missing. It should let you find those two rows and explain each rejection.

After correcting them, check how to run the transfer again without recreating the 18 orders already present. Also compare amounts, dates and customer links. Twenty rows at the end are not enough if they contain duplicates or incorrect information.

Organise the day of the change

Decide which tool will receive new entries and from when. If you temporarily use both, choose a reference version and someone responsible for carrying changes across. Avoid letting everyone freely correct their own file.

Try a complete work cycle and prepare a possible return. Who decides to stop the changeover? Where are the new entries that must be recovered? A successful trial reduces uncertainty without guaranteeing that no problem will arise.

Keep a useful record

Keep the transfer report and protect the old file as read-only for as long as it remains necessary. Decide who may consult it. If you are still unsure about changing tools, our guide to replacing Excel with an app helps you decide first.