One Tier, Two Tier and Three Tier Architecture
Tier architecture describes how many machines or layers a database request passes through. One tier is local, two tier puts the application on the cli...
Database management system concepts.
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Tier architecture describes how many machines or layers a database request passes through. One tier is local, two tier puts the application on the cli...
Where databases are actually used, and what sits inside a running database system: the DBMS software, the stored database, the catalog, the applicatio...
A schema is the design of a database and rarely changes. An instance is the data in it at one moment and changes constantly. Metadata is the stored de...
Data independence is the ability to change a schema at one level without changing the level above. Physical independence is easy to achieve; logical i...
The ANSI-SPARC architecture separates a database into external, conceptual and internal levels. That separation is what makes data abstraction and dat...
A database system serves naive users, application programmers, sophisticated users and specialised users, and is run by a database administrator whose...
A DBMS buys controlled redundancy, enforced integrity, sharing, security, recovery and independence. It charges for them in cost, complexity, hardware...
The file based approach fails on redundancy, inconsistency, isolation, atomicity, concurrency, security and integrity. Each failure maps to one specif...
A DBMS is the software layer between users and stored data. It exists to give many users controlled, concurrent, recoverable and consistent access to...
Data is raw recorded fact, information is data placed in context, and a database is an organised, shared, self describing collection of related data...