Php-problems between post data on two pages

Fill in the first page and post it to another page. The post parameters are stored in the database, for example, $ ID $ _ POST [& quot; ID & quot;]; $ B $ _ POST [& quot; B & quot;]; $ S $ _ POST [& quot; S & quot;]; where ID, B and X are the attributes in the table in the database. they do not need to be defined when used. in this case, I need to introduce two attributes such as $ z $ _ POST [& quot; z & quot;]; $ X $ _ POST [& quot; x & quot;] z and x are not stored in the database. problems occur when running the program. "Unde php Data Database index post

Enter something in the first page and post it to another page. The post parameters are stored in the database.
For example, $ ID = $ _ POST ["ID"]; $ B = $ _ POST ["B"]; $ S = $ _ POST ["S"];
The ID, B, and X are the attributes in the table in the database. they are not required to be defined when used. in this case, I need to introduce two attributes such as $ z = $ _ POST ["z"]; $ X = $ _ POST ["x"] z and x parameters that are not stored in the database, and the "Undefined index" Undefined index is an issue when running the program, how can I solve this problem? it is best not to write z and x into the database.