Ways of validating data
Data validation is implemented via rules defined in Excel's user interface on the Data tab of the ribbon.It is important to understand that data validation can be easily defeated.If a user copies data from a cell without validation to a cell with data validation, the validation is destroyed (or replaced).Data validation is a good way to let users know what is allowed or expected, but it is Data validation is defined in a window with 3 tabs: Settings, Input Message, and Error Alert: The settings tab is where you enter validation criteria.
For example, when style is set to "Stop", invalid data triggers a window with a message, and the input is not allowed.
List - only values from a predefined list are allowed.
The values are presented to the user as a dropdown menu control.
For example, to restrict entries to the actions "BUY", "HOLD", or "SELL" you can enter these values separated with commas as seen below: When applied to a cell in the worksheet, the dropdown menu works like this: Another way to supply values to a dropdown menu is to use a worksheet reference. small, medium, etc.) in the range F3: F6, you can supply this range directly inside the data validation settings window: Note the range is entered as an absolute address to prevent it from changing as the data validation is applied to other cells. For example, with the named range called "sizes" for F3: F7, you can enter the name directly in the window, starting with an equal sign: Named ranges are automatically absolute, so they won't change as the data validation is applied to different cells.
If named ranges are new to you, this page has a good overview and a number of related tips.