DataSunrise is sponsoring RSA Conference2024 in San Francisco, please visit us in DataSunrise's booth #6178

Data Masking in MySQL

Data Masking in MySQL

Data Masking in MySQL content image


Data masking is a crucial technique for safeguarding sensitive information in databases. It involves obscuring or altering data to protect it from unauthorized access while maintaining its usability for testing, development, or analytics purposes. MySQL, a popular open-source relational database management system, offers several methods to implement data masking effectively.

Why Data Masking Matters

In many industries, organizations handle sensitive data such as personally identifiable information (PII), financial records, or health information. We must protect this data to comply with privacy regulations, prevent data breaches, and maintain customer trust. However, developers, testers, and analysts often need access to realistic data to perform their tasks effectively.

Data masking creates a secure version of the database. This version resembles the original data. However, it does not display any sensitive information. This allows teams to work with near-real data while minimizing the risk of data leaks or misuse.

Data Masking Techniques in MySQL

MySQL offers several built-in functions and techniques that users can use to mask sensitive data.

  1. One way to mask sensitive data is by replacing part of it with a set string or characters. For example, you can use the SUBSTRING_INDEX() function to extract a part of a string and concatenate it with a masking string.
  2. Example:

    UPDATE customers SET email = CONCAT(SUBSTRING_INDEX(email, '@', 1), '');

    This query changes the email column in the customers table by adding “” to the username part of the email to mask the domain.

  3. Generate random data in MySQL using the RAND() function to create realistic but fake data for testing purposes. This is particularly useful for masking numerical or date values.
  4. Example:

    UPDATE employees SET salary = ROUND(RAND() * 100000);

    This query updates the “salary” column in the “employees” table with a randomly generated number between 0 and 100,000.

  5. Data Shuffling: Data shuffling involves randomly rearranging the values within a column while maintaining the overall distribution. This method masks actual values while keeping statistical properties intact for analyzing or testing.
  6. Create a temporary table called temp_employees with the same data as employees but in a random order.

    Then update the employees table by matching the ids with the temp_employees table:

    SET e.first_name = t.first_name,
    e.last_name = t.last_name;
    DROP TABLE temp_employees;

    These commands mix up employee names to create a temporary table. They then update the original table with the mixed-up values. Finally, we delete the temporary table.

  7. Conditional Masking: In some cases, you may want to apply different masking techniques based on certain conditions. MySQL’s CASE expression allows you to specify multiple masking rules based on the data’s characteristics.

Update the phone numbers for customers based on their country. If the country is US, add +1 to the beginning of the phone number. If the country is UK, add +44 to the beginning. For all other countries, add a random number between 1 and 100 followed by the existing phone number.

This query masks the “phone” column in the “customers” table differently based on the customer’s country.

A Comprehensive Example

Let’s look at a harder example that uses different ways to hide important information in an online shopping database.

Suppose we have a “users” table with the following structure:

| id | first_name | last_name | email            | phone    |
| 1  | John       | Doe       | [email protected] | 123456   |
| 2  | Jane       | Smith     | [email protected] | 789012   |
| 3  | Bob        | Johnson   | [email protected]  | 345678   |

To mask this data, we can use a combination of substring replacement, random data generation, and data shuffling:


-- Create a temporary table with shuffled user data
-- Mask the email addresses
UPDATE users u
JOIN temp_users t ON =
-- Mask the phone numbers
UPDATE users u
JOIN temp_users t ON =
SET = CONCAT('*****', SUBSTRING(, -3));
-- Shuffle the first and last names
UPDATE users u
JOIN temp_users t ON =
    u.first_name = t.first_name,
    u.last_name = t.last_name;
-- Drop the temporary table
DROP TABLE temp_users;

After executing these queries, the masked “users” table would look like this:

| id | first_name | last_name | email                  | phone    |
| 1  | Bob        | Smith     | [email protected]       | *****456 |
| 2  | John       | Johnson   | [email protected]       | *****012 |
| 3  | Jane       | Doe       | [email protected]        | *****678 |

As you can see, I masked the email addresses by replacing the domain with “”. I have partially hidden the phone numbers.

Asterisks have replaced the first five digits. Someone mixed up the first and last names. The overall pattern remains the same.

Implementing Data Masking in Your MySQL Workflow

To incorporate data masking into your MySQL workflow, consider the following best practices:

  1. Create separate masked databases for non-production environments like development, testing, and analytics. This ensures that these processes do not accidentally expose sensitive data.
  2. Automate the masking process using MySQL stored procedures or scripts. This makes it easier to refresh the masked data periodically and ensures consistency across different environments.
  3. Document your masking rules and techniques thoroughly. This helps maintain transparency and allows for easier auditing and compliance checks.
  4. Regularly review and update your masking strategies to keep up with changing data privacy regulations and best practices.


Data masking is an essential technique for protecting sensitive information in MySQL databases while enabling developers, testers, and analysts to work with realistic data. You can use MySQL’s functions to create sanitized versions of your databases. This helps maintain structure and distribution without revealing sensitive data. You can use techniques like substring replacement, random data generation, shuffling, and conditional masking for this purpose.

Implementing data masking in your MySQL workflow requires careful planning, automation, documentation, and regular reviews to ensure the ongoing protection of sensitive information.

By using these tips, you can find the right balance between protecting data and making it easy to use. This will help your organization grow and innovate while keeping your customers’ trust and following regulations.


MySQL Authentication

MySQL Authentication

Learn More

Need Our Support Team Help?

Our experts will be glad to answer your questions.

General information:
[email protected]
Customer Service and Technical Support:
Partnership and Alliance Inquiries:
[email protected]