Can I check the room number online when I open a room with my ID card?

I can't. Identity card belongs to personal privacy information and cannot be obtained and used at will. Therefore, you can't directly use your ID card to check the information of the room opening record, let alone find the hotel room number online. Hotels must abide by relevant laws and regulations when collecting personal information, strictly protect and restrict the use of personal information of guests, and must not disclose or provide personal information to any third party. The records of guests opening rooms in hotels also need to be kept confidential. Only public security organs or legal institutions can issue certificates to obtain relevant information to a certain extent, but this needs to comply with relevant laws, regulations and procedures.