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an overall enterprise architecture that favors shared data models [5] over allowing each application to have its own, idiosyncratic data model. Even an extreme database-centric architecture called RDBMS-only architecture [6] [7] has been proposed, in which the three classic layers of an application are kept within the RDBMS. This architecture ...
The database schema is the structure of a database described in a formal language supported typically by a relational database management system (RDBMS). The term " schema " refers to the organization of data as a blueprint of how the database is constructed (divided into database tables in the case of relational databases ).
One of the architecture techniques is the split between managing transaction data and (master) reference data. Another is splitting data capture systems from data retrieval systems (as done in a data warehouse). Technology drivers These are usually suggested by the completed data architecture and database architecture designs.
Some - can only reverse engineer the entire database at once and drops any user modifications to the diagram (can't "refresh" the diagram to match the database) Forward engineering - the ability to update the database schema with changes made to its entities and relationships via the ER diagram visual designer Yes - can update user-selected ...
SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Edgar F. Codd [12] in the early 1970s. [13] This version, initially called SEQUEL (Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original quasirelational database management system, System R, which a group at IBM San ...
Pros and cons efficient for exact matches on key field; not suitable for range retrieval, which requires sequential storage; calculates where the record is stored based on fields in the record; hash functions ensure even spread of data; collisions are possible, so collision detection and restoration is required
The internal structure of the database should be unaffected by changes to the physical aspects of the storage: For example, a changeover to a new disk. The three levels are: External Level (User Views): A user's view of the database describes a part of the database that is relevant to a particular user. It excludes irrelevant data as well as ...
A logical data model or logical schema is a data model of a specific problem domain expressed independently of a particular database management product or storage technology (physical data model) but in terms of data structures such as relational tables and columns, object-oriented classes, or XML tags.