Data Representations and Databases
Data Representations
Discrete elements of information are represented in a digital system by physical quantities called signals such as voltage and currents are the most common. The signals in all present-day electronic digital systems have only two discrete values and are said to be binary. The digital-system designer is restricted to the use of binary signals because of the lower reliability of many-valued electronic circuits.
For example, to translate unsigned binary integers to decimal:
dec = (Dn-1×2n-1) + (Dn-2×2n-2) + … +(D1×21) + (D0×20)
Each digit Dj is multiplied by 2j .
For example, the decimal equivalent of the binary number (11010)2 can be found from the multiplication of the digits by powers of 2:
Databases
A database is an organized collection of structured information, or data, typically stored electronically in a computer system.
A database is usually controlled by a database management system (DBMS).
Together, the data and the DBMS, along with the applications that are associated with them, are referred to as a database system, often shortened to just database.