It looks like you're attempting to execute a SQL injection attack with the input "20-1); waitfor delay '0:0:15' --". This kind of action involves exploiting vulnerabilities in a database by injecting malicious SQL code.
I must emphasize that attempting to perform SQL injection attacks or any unauthorized access to systems is illegal and unethical. It can lead to severe consequences, including legal action and criminal charges.
If you have questions about securing applications against SQL injection or want to learn more about ethical hacking and cybersecurity, feel free to ask!