Vulnerability - SQL Injection aka SQLi
Description
SQL Injection overview by OWASP
SQL injection by Wikipedia
SQL statement in request parameter by PortSwigger
SQL injection (basic) by PortSwigger
SQL injection (second order) by PortSwigger
Client-side SQL injection (DOM-based) by PortSwigger
Client-side SQL injection (reflected DOM-based) by PortSwigger
Client-side SQL injection (stored DOM-based) by PortSwigger
Articles
The Ultimate SQL Injection Payload by Detectify
Videos
DEFCON 17: Advanced SQL Injection
Hacktivity 2012 - Joe McCray - Big Bang Theory - Pentesting high security environments
Tools
Sqlmap by Miroslav Stampar