34,34,34,34# | -3216' Union All Select

: If the page displays the number "34" several times, it confirms the site is vulnerable to SQL injection.

: In MySQL, this symbol marks the rest of the original query as a comment , effectively deleting the remaining code (like WHERE clauses or authentication checks) to bypass security. Purpose of This "Piece" -3216' UNION ALL SELECT 34,34,34,34#

: This part creates a "fake" row of data. Attackers use this to determine the exact number of columns required for the UNION to work, as both queries must have the same number of columns. : If the page displays the number "34"

: This is an intentional "invalid" input (like a negative ID) designed to break the original SQL query's logic and ensure the database returns no results for the first part of the operation. Attackers use this to determine the exact number