Database Administration Questions

The Mirror can turn everything around without moving.

The law of conservation of mass states that in any closed system the mass of the system is neither created nor destroyed over time i.e, the mass cannot be changed overtime.

Hence, the given statement is true.

The difference between Union and Union all is that Union all will not eliminate duplicate rows, instead it just pulls all rows from all tables fitting your query specifics and combines them into a table. A UNION statement effectively does a SELECT DISTINCT on the results set.

A search engine is a set of programs which enables users to search documents and files ihe world wide web.

Common search engines are Google, Yahoo, Bing,...

In the mesh topology, each computer is connected to the other with a separate physical link in a network. It is most reliable topology as the network does not get down in case one of the nodes is failed.

A candidate key is a column, or set of columns, in a table that can uniquely identify any database record without referring to any other data. Each table may have one or more candidate keys, but one candidate key is unique, and it is called the primary key.

It is a single computer in a network reserved for serving the needs of the network.