ISO9000ISO9000 is an international standard of quality management and quality assurance. It certifies the companies that they are documenting the quality system elements which are needed to run a efficient and quality system.SEI-CMMSEI (Software Engineering Institute) - Capability Maturity Model (CMM) is specifically for software organizations to certify them at which level, they are following and maintaining the quality standards.Following are the important differences between ISO9000 and SEI-CMM.Sr. No.KeyISO9000SEI-CMM.1DefinitionISO9000 is an international standard of quality management and quality assurance. It certifies the companies that they are documenting the quality system elements which are needed to run a efficient and quality ... Read More

Public Switched Telephone Network (PSTN) is an agglomeration of an interconnected network of telephone lines owned by both governments as well as commercial organizations. Properties of PSTN It is also known as Plain Old Telephone Service (POTS) It has evolved from the invention of telephone by Alexander Graham Bell. The individual networks can be owned by national government, regional government or private telephone operators. Its main objective is to transmit human voice in a recognizable form. It is an aggregation of circuit-switched networks of the world. Originally, it was an entirely analog network laid with copper cables ... Read More

The different types of keys in DBMS are −Candidate Key - The candidate keys in a table are defined as the set of keys that is minimal and can uniquely identify any data row in the table.Primary Key - The primary key is selected from one of the candidate keys and becomes the identifying key of a table. It can uniquely identify any data row of the table.Super Key - Super Key is the superset of primary key. The super key contains a set of attributes, including the primary key, which can uniquely identify any data row in the table.Composite Key -  If ... Read More