It looks like you're trying to perform a SQL injection test using a query that includes the PG_SLEEP function, which is specific to PostgreSQL databases. SQL injection is a method used to manipulate a database by injecting arbitrary SQL code into a query, potentially allowing an attacker to gain unauthorized access to data or execute unintended commands.
If you have a legitimate purpose for learning about SQL injection, such as improving security measures for web applications, I recommend studying it in a controlled environment like a penetration testing lab or through legal training courses on cybersecurity.
Please remember that unauthorized access to databases or attempts to manipulate them without permission is illegal and unethical. Always ensure you have permission to test any system or application for vulnerabilities. If you have questions about SQL security or prevention techniques, feel free to ask!