Answer:
columns, rows
Explanation:
In Computer programming, a atabase schema refers to the logical design of the database while the database instance refers to a snapshot of the data found in a database at a given instant in time.
Basically, in database management, the term "schema" is used to denote a representation of data while the term "instance" is used to denote an instance of time.
A database schema is a structure which is typically used to represent the logical design of the database and as such represents how data are stored or organized and the relationships existing in a database management system. There are two (2) main categories of a database schema; physical database schema and logical database schema.
Also, a database instance is a snapshot of the data in the database at a given instant in time and as such represents an operational database by following the conditions, validation and constraints set for a database management system.
These data can be stored or organized in a database management system through the use of multiple-column record formats.
In a multiple-column record of a data file, columns represent different variables and rows represent different cases (respondents) such as experimental data, independent observations etc.
Answer:
optical sensors
Explanation:
optical sensors measure the amount of gases like carbon dioxide and carbon monoxide in the air
Answer:b)Reserve Room, Enter Contact Information, Enter Reservation Detail
Explanation: The use case is described as actors , actors goal, usage of use cases, units of scope and initial point and terminating point of use cases .
The situation mentioned in the question will take place for the reservation of the room through the instances in the form like filling the contact details for the identification , filling out reservation information as well for getting the knowledge about the room requirement by the person.
These details help in reaching out the particular person if required, number of days he wants to book the room,any extra facility he would like to have etc. After these detail filling activity the room can be reserved successfully.Thus , the most appropriate option is option (b).
Other options are incorrect because room reservation cannot be done without any formality as mentioned in the question and entering contact detail and reservation detail one by one.