-2151 Union — All Select 34,34,34,34,34,34,34,34,34#

The string you provided looks like a snippet of a attack, often used by researchers or hackers to test if a database is vulnerable [1, 2].

Working on a challenge or a security audit? -2151 UNION ALL SELECT 34,34,34,34,34,34,34,34,34#

Trying to these types of attacks in your own code? The string you provided looks like a snippet