MS Excel data validation feature allows you to set up certain rules that dictate what can be entered into a cell. For example, you may want to limit data entry in a particular cell to whole numbers between 0 and 10. If the user makes an invalid entry, you can display a custom message as shown below
To specify the type of data allowable in a cell or range, follow the steps below while you refer to which shows all three tabs of the Data Validation dialog box.
Select the cell or range.
Choose Data » Data Tools » Data Validation. Excel displays its Data Validation dialog box having 3 tabs settings, Input Message and Error alert.
Here you can set the type of validation you need.Choose an option from the Allow drop-down list.The contents of the Data Validation dialog box will change, displaying controls based on your choice.
Any Value : Selecting this option removes any existing data validation.
Whole Number : The user must enter a whole number.For example, you can specify that the entry must be a whole number greater than or equal to 50.
Decimal : The user must enter a number. For example, you can specify that the entry must be greater than or equal to 10 and less than or equal to 20.
List : The user must choose from a list of entries you provide.You will create drop-down list with this validation. You have to give input ranges then those values will appear in the drop-down.
Date : The user must enter a date. You specify a valid date range from choices in the Data drop-down list. For example, you can specify that the entered data must be greater than or equal to January 1, 2013, and less than or equal to December 31, 2013.
Time : The user must enter a time. You specify a valid time range from choices in the Data drop-down list. For example, you can specify that the entered data must be later than 12:00 p.m.
Text Length : The length of the data (number of characters) is limited. You specify a valid length by using the Data drop-down list. For example, you can specify that the length of the entered data be 1 (a single alphanumeric character).
Custom : To use this option, you must supply a logical formula that determines the validity of the user’s entry (a logical formula returns either TRUE or FALSE).
Input Message tab
You can set the input help message with this tab. Fill the title and Input message of the Input message tab and the input message will appear when cell is selected..
Error Alert Tab
You can specify error message with this tab. Fill the title and error message. Select the style of the error as stop, warning or Information as per you need.