Look at the screen. You might see something like:
OWASP Security Shepherd's SQL Injection Challenge 5 focuses on Boolean-based Blind SQL Injection, requiring users to extract hidden data by inputting TRUE/FALSE queries to infer information. Attackers exploit this by analyzing application responses to guess characters one-by-one using SQL functions like SUBSTRING() Sql Injection Challenge 5 Security Shepherd
5' AND (ASCII(SUBSTRING((SELECT hash FROM keys WHERE id=1), [position], 1)) ) > [ascii_value] AND '1'='1 Look at the screen