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  2. Logical schema - Wikipedia

    en.wikipedia.org/wiki/Logical_schema

    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.

  3. ANSI-SPARC Architecture - Wikipedia

    en.wikipedia.org/wiki/ANSI-SPARC_Architecture

    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 ...

  4. View (SQL) - Wikipedia

    en.wikipedia.org/wiki/View_(SQL)

    If the database system can determine the reverse mapping from the view schema to the schema of the underlying base tables, then the view is updatable. INSERT, UPDATE, and DELETE operations can be performed on updatable views. Read-only views do not support such operations because the DBMS cannot map the changes to the underlying base tables.

  5. Data independence - Wikipedia

    en.wikipedia.org/wiki/Data_independence

    Modifications at the logical level are necessary whenever the logical structure of the database is altered (for example, when money-market accounts are added to banking system). Logical Data independence means if we add some new columns or remove some columns from table then the user view and programs should not change.

  6. Database model - Wikipedia

    en.wikipedia.org/wiki/Database_model

    A database model is a type of data model that determines the logical structure of a database. It fundamentally determines in which manner data can be stored, organized and manipulated. The most popular example of a database model is the relational model , which uses a table-based format.

  7. View model - Wikipedia

    en.wikipedia.org/wiki/View_model

    The four views of the model are logical, development, process and physical view: The four views of the model are concerned with : Logical view: is concerned with the functionality that the system provides to end-users. Development view: illustrates a system from a programmers perspective and is concerned with software management.

  8. Relational model - Wikipedia

    en.wikipedia.org/wiki/Relational_model

    A database organized in terms of the relational model is a relational database. ... as in the relational model, with a logical view, as in logic programming.

  9. Codd's 12 rules - Wikipedia

    en.wikipedia.org/wiki/Codd's_12_rules

    Codd's twelve rules [1] are a set of thirteen rules (numbered zero to twelve) proposed by Edgar F. Codd, a pioneer of the relational model for databases, designed to define what is required from a database management system in order for it to be considered relational, i.e., a relational database management system (RDBMS).