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  2. SQLSTATE - Wikipedia

    en.wikipedia.org/wiki/SQLSTATE

    The following table lists the standard-conforming values - based on SQL:2011. [1] The table's last column shows the part of the standard that defines the row. If it is empty, the definition originates from part 2 Foundation .

  3. Consistency (database systems) - Wikipedia

    en.wikipedia.org/wiki/Consistency_(database_systems)

    In database systems, consistency (or correctness) refers to the requirement that any given database transaction must change affected data only in allowed ways. Any data written to the database must be valid according to all defined rules, including constraints, cascades, triggers, and any combination thereof. This does not guarantee correctness ...

  4. Referential integrity - Wikipedia

    en.wikipedia.org/wiki/Referential_integrity

    An example of a database that has not enforced referential integrity. In this example, there is a foreign key (artist_id) value in the album table that references a non-existent artist — in other words there is a foreign key value with no corresponding primary key value in the referenced table.

  5. Entity integrity - Wikipedia

    en.wikipedia.org/wiki/Entity_integrity

    The PK is a not empty set of attributes (or columns). The same format applies to the foreign key (abbreviated FK) because each FK matches a preexistent PK. Each of attributes being part of a PK (or of a FK) must have data values (such as numbers, letters or typographic symbols) but not data marks (also known as NULL marks in SQL world).

  6. Third normal form - Wikipedia

    en.wikipedia.org/wiki/Third_normal_form

    A database relation (e.g. a database table) is said to meet third normal form standards if all the attributes (e.g. database columns) are functionally dependent on solely a key, except the case of functional dependency whose right hand side is a prime attribute (an attribute which is strictly included into some key).

  7. Database transaction - Wikipedia

    en.wikipedia.org/wiki/Database_transaction

    For example: when execution prematurely and unexpectedly stops (completely or partially) in which case many operations upon a database remain uncompleted, with unclear status. To provide isolation between programs accessing a database concurrently. If this isolation is not provided, the programs' outcomes are possibly erroneous.

  8. Fifth normal form - Wikipedia

    en.wikipedia.org/wiki/Fifth_normal_form

    If such a table is not normalized to 5NF, the burden of maintaining the logical consistency of the data within the table must be carried partly by the application responsible for insertions, deletions, and updates to it; and there is a heightened risk that the data within the table will become inconsistent. In contrast, the 5NF design excludes ...

  9. SQL syntax - Wikipedia

    en.wikipedia.org/wiki/SQL_syntax

    Title Authors ----- ----- SQL Examples and Guide 4 The Joy of SQL 1 An Introduction to SQL 2 Pitfalls of SQL 1 Under the precondition that isbn is the only common column name of the two tables and that a column named title only exists in the Book table, one could re-write the query above in the following form: