Back to Formula Examples

Data Validation Techniques

Learn how to ensure data integrity with Excel's powerful validation tools and formulas.

Custom Validation Formulas

While Excel offers built-in data validation tools, you can create more complex validation rules using custom formulas. These formulas can check for specific patterns, relationships between cells, or business logic requirements.

The Formula Solution

=AND(LEN(A2)=10,ISNUMBER(--LEFT(A2,3)),ISNUMBER(--RIGHT(A2,6)),MID(A2,4,1)="-")

This formula validates a custom ID format (e.g., "123-456789") by checking:

  • The total length is exactly 10 characters
  • The first 3 characters can be converted to a number
  • The last 6 characters can be converted to a number
  • The 4th character is a hyphen

You can use this formula in Excel's Data Validation settings by selecting "Custom" and entering this formula.

Useful Validation Formulas

Email Format Validation

=AND(ISNUMBER(FIND("@",A2)),ISNUMBER(FIND(".",A2,FIND("@",A2))))

Basic check for @ and . in the right order

Date Range Validation

=AND(A2>=DATE(2023,1,1),A2<=TODAY())

Ensures date is between Jan 1, 2023 and today

Unique Value Check

=COUNTIF($A$2:$A$100,A2)=1

Ensures the value appears only once in the range

Dependent Dropdown Lists

=INDIRECT("List_"&A2)

Creates a dependent dropdown based on another cell's value

This is a placeholder for an interactive example of data validation formulas.

Future implementation will include an interactive Excel-like interface to try these formulas with sample data.

Implementing Data Validation

To use these formulas in Excel's Data Validation:

  1. Select the cell or range you want to validate
  2. Go to Data tab > Data Tools group > Data Validation
  3. In the Settings tab, select "Custom" from the dropdown
  4. Enter your validation formula in the Formula field
  5. Set up error messages in the Error Alert tab

Remember that your formula must return TRUE for valid data and FALSE for invalid data.

Real-World Applications

Data validation is crucial for many business tasks:

  • Ensuring data entry meets specific business requirements
  • Validating formatted codes like SKUs, employee IDs, or account numbers
  • Creating cascading or dependent dropdown lists
  • Preventing duplicate entries in databases
  • Enforcing date ranges for reporting periods

How ExcelGPT Can Help

ExcelGPT can assist you with data validation by:

  • Creating custom validation formulas for your specific data requirements
  • Setting up complex dependent validation rules
  • Explaining how to implement validation in your worksheets
  • Troubleshooting validation errors or unexpected behavior
  • Converting business requirements into validation rules
    v1.0.0