Christen is a renowned SQL penetration testing specialist in the US. A multinational ecommerce company hired him to check for vulnerabilities in the SQL database. Christen decided to perform SQL…

Christen is a renowned SQL penetration testing specialist in the US. A multinational ecommerce company hired him to check for vulnerabilities in the SQL database. Christen decided to perform SQL injection by injecting a malicious query into the e-commerce website which used SQL database to store the products and customers' information. The SQL injection caused an error and displayed additional information about the database schema. Which of the following testing techniques is Christen using?