How to prevent duplicate entry in Google sheets?

In Google sheets, how could you prevent duplicate entry in a specific column? Actually, the Data validation in Google sheets can help you to finish this task.

Prevent duplicate entry in Google sheets with Data validation

Prevent duplicate entry in Microsoft Excel with Kutools for Excel


Prevent duplicate entry in a range of cells in Excel worksheet:

If you need to prevent some duplicate values when entering into a range of cells in your worksheet, the Kutools for Excel's Prevent Duplicate feature can help you to finish this task as quickly as possible.

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Prevent duplicate entry in Google sheets with Data validation

Normally, the Data validation in Google sheets can do you a favor, please do as this:

1. Select a list of cells that you want to prevent duplicates, and then click Data > Data validation, see screenshot:

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2. In the Data validation dialog box:

(1.) Choose Custom formula is from the drop down list, and enter this formula: =countif(A$2:A2,A2)=1 into the Criteria text box;

(2.) Then select Reject input option from the On invalid data section.

Note: In the above formula, A2 is the start cell of the column that you want to use.

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3. Then click Save button, from now on, when duplicate data is entered in that specific column, a warning box will pop out to remind you, see screenshot:

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Prevent duplicate entry in Microsoft Excel with Kutools for Excel

In Excel worksheet, you can prevent duplicate entries by using a useful tool-Kutools for Excel, with its Prevent Duplicate feature, you can quickly finish this task in Excel.

Kutools for Excel : with more than 300 handy Excel add-ins, free to try with no limitation in 60 days. 

After installing Kutools for Excel, please do as this:

1. Select the cells that you want to prevent duplicates, and then click Kutools > Prevent Typing > Prevent Duplicate, see screenshot:

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2. And then a prompt box is popped out to remind you if there are Data Validation cells in your selected range, it be removed when applying this feature, see screenshot:

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3. Then click Yes button, and a prompt box will pop out as following screenshot shown:

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4. Then click OK button, now, when you enter duplicate value in the specified column, a warning box will pop out, see screenshot:

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    Moi · 8 months ago
    Hola quiero ocupar la Validación de datos caja de diálogo en las formas de Google, para evitar datos repetidos... cuando aplico la formula

    Seleccionando la columna A completa utilizó en validar datos utilizo la formula personalizada =countif(A$2:A2,A2)=1 en el Criterios caja de texto;

    No me permite ingresar ningún valor... Alguna idea de que puedo estar haciendo mal?