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  2. Referential integrity - Wikipedia

    en.wikipedia.org/wiki/Referential_integrity

    Referential integrity is a property of data stating that all its references are valid. In the context of relational databases , it requires that if a value of one attribute (column) of a relation (table) references a value of another attribute (either in the same or a different relation), then the referenced value must exist.

  3. Data integrity - Wikipedia

    en.wikipedia.org/wiki/Data_integrity

    An example of a data-integrity mechanism is the parent-and-child relationship of related records. If a parent record owns one or more related child records all of the referential integrity processes are handled by the database itself, which automatically ensures the accuracy and integrity of the data so that no child record can exist without a parent (also called being orphaned) and that no ...

  4. Entity integrity - Wikipedia

    en.wikipedia.org/wiki/Entity_integrity

    Entity integrity is concerned with ensuring that each row of a table has a unique and non-null primary key value; this is the same as saying that each row in a table represents a single instance of the entity type modelled by the table.

  5. Foreign key - Wikipedia

    en.wikipedia.org/wiki/Foreign_key

    Because the database management system enforces referential constraints, it must ensure data integrity if rows in a referenced table are to be deleted (or updated). If dependent rows in referencing tables still exist, those references have to be considered. SQL:2003 specifies 5 different referential actions that shall take place in such ...

  6. Database normalization - Wikipedia

    en.wikipedia.org/wiki/Database_normalization

    Database normalization is the process of structuring a relational database accordance with a series of so-called normal forms in order to reduce data redundancy and improve data integrity. It was first proposed by British computer scientist Edgar F. Codd as part of his relational model .

  7. Third normal form - Wikipedia

    en.wikipedia.org/wiki/Third_normal_form

    Third normal form (3NF) is a database schema design approach for relational databases which uses normalizing principles to reduce the duplication of data, avoid data anomalies, ensure referential integrity, and simplify data management.

  8. Data hierarchy - Wikipedia

    en.wikipedia.org/wiki/Data_hierarchy

    It is particularly important in databases with referential integrity, third normal form, or perfect key. "Data hierarchy" is the result of proper arrangement of data without redundancy. Avoiding redundancy eventually leads to proper "data hierarchy" representing the relationship between data, and revealing its relational structure.

  9. Database transaction - Wikipedia

    en.wikipedia.org/wiki/Database_transaction

    Databases and other data stores which treat the integrity of data as paramount often include the ability to handle transactions to maintain the integrity of data. A single transaction consists of one or more independent units of work, each reading and/or writing information to a database or other data store.