Explanation
Data validation rules are triggered when a user adds or changes a cell value.
The TODAY function returns today’s date (recalculated an on on-going basis). The AND function takes multiple logical expressions and returns TRUE only when all expressions return TRUE. In this case, we need to test two conditions:
The first condition checks that the input is greater than today:
C5>TODAY()
The second condition checks that the input is less than today + 30:
C5<=(TODAY()+30)
(Dates are just serial numbers in Excel, so we can simply add 30).
If both logical expressions return TRUE, the AND function returns TRUE and validation succeeds. If either expressions returns FALSE, data validation fails.
Note: Cell references in data validation formulas are relative to the upper left cell in the range selected when the validation rule is defined, in this case C5.
Data Validation Guide | Data Validation Formulas | Dependent Dropdown Lists
Explanation
Data validation rules are triggered when a user adds or changes a cell value.
This custom validation formula simply checks the year of any date against a hard-coded year value using the YEAR function.
When a user enters a value, the YEAR function extracts and compares the year to 2016:
=YEAR(C5)=2016
When the years match, the expression returns TRUE and validation succeeds. If the years don’t match, or if the YEAR function is not able to extract a year, validation fails.
Date this year
To allow only dates in the current year, you can adjust the formula like this:
=YEAR(C5)=YEAR(TODAY())
The TODAY function will return the current date on an on-going basis, so formula returns TRUE only when a date is in the current year.
Note: Cell references in data validation formulas are relative to the upper left cell in the range selected when the validation rule is defined, in this case C5.
Data Validation Guide | Data Validation Formulas | Dependent Dropdown Lists
