- Select the cell/cells where you want to apply the data validation.
- Select Data → Data Validation. You can also apply data validation to a group of cells, entire rows/columns etc.
- Data Validation dialog appears on the Right. Select the "Custom" criteria from the drop-down and enter the formula
In this example, want the text to start with "ABC-", so we selected and cell A2 and used the formula "Countif(A2,"ABC-*")" to set the validation for A2. This validation now can be copied to other cells too.
- (Optional) Enter the input message for users
A message that will be displayed when the user hovers over/selects the cell can be entered here.
If you want to Ignore the blank cells from the data validation, toggle the switch "Ignore Blank Cells" to ON.
- (Optional) Enter Message at input of incorrect values.
In the lower section of the Dialog, you can choose to display a message when the user enters invalid data. To display an alert, select the "Show Alert" box
Different Alert types are "Error, Warning and Information". Select the required Alert type, title and the message you want to display.
- Click OK once the values are selected.
- Note: Any incorrect values will be circled red and hovering over/selecting the cells will show the input message.
- Note: Entering Incorrect value will show up the error message
See Also: How to use Data Validation feature