We can illustrate this technique by adding such a validation data control to the Membership Number column as follows: Select all existing data cells in the column in question.

The Data Validation feature in Excel 2013 offers a List option to confine selections in a cell to a preconfigured series of values. This selection can further influence the values in another list ...

You can easily create a drop-down list in Excel to limit the values that can be entered in a column. This data validation helps prevent mistakes, such as misspellings.

A common use of data validation is to create a drop-down list. Use it to restrict the type of data that users enter into an Excel cell.

Learn how to use a data validation control to allow users to select when to run multiple VBA procedures in Microsoft Excel.

However, because Excel largely relies on you having a consistent grid of individual cells placed in rows and columns, merging cells causes issues when you come to make changes to your data.