If a database is vulnerable, it will try to process this calculation. Because the resulting string (a mix of letters and the number 1) cannot be converted to a NUMERIC type, the database will throw an error message . An attacker looks for that specific error to confirm the database is open to manipulation.
It looks like you've shared a snippet of rather than a typical search topic. Specifically, this string is designed to test for vulnerabilities in a database by using PostgreSQL-specific syntax ( ::text and CHR functions). If a database is vulnerable, it will try
The SELECT (CASE WHEN (5241=5241) THEN 1 ELSE 0 END) is a "true or false" test. Since 5241 always equals 5241, it returns 1 . If a database is vulnerable