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  2. Hi/Lo algorithm - Wikipedia

    en.wikipedia.org/wiki/Hi/Lo_algorithm

    Hi/Lo is an algorithm and a key generation strategy used for generating unique keys for use in a database as a primary key. It uses a sequence-based hi-lo pattern to generate values. It uses a sequence-based hi-lo pattern to generate values.

  3. Unique key - Wikipedia

    en.wikipedia.org/wiki/Unique_key

    Key Name Definition Simple A key made from only one attribute. Concatenated A key made from more than one attribute joined together as a single key, such as part or whole name with a system generated number appended as often used for E-mail addresses. Compound: A key made from at least two attributes or simple keys, only simple keys exist in a ...

  4. Candidate key - Wikipedia

    en.wikipedia.org/wiki/Candidate_key

    A candidate key, or simply a key, of a relational database is any set of columns that have a unique combination of values in each row, with the additional constraint that removing any column could produce duplicate combinations of values. A candidate key is a minimal superkey, [1] i.e., a superkey that does not contain a smaller one. Therefore ...

  5. Primary key - Wikipedia

    en.wikipedia.org/wiki/Primary_key

    In the relational model of databases, a primary key is a designated attribute that can reliably identify and distinguish between each individual record in a table.The database creator can choose an existing unique attribute or combination of attributes from the table (a natural key) to act as its primary key, or create a new attribute containing a unique ID that exists solely for this purpose ...

  6. Surrogate key - Wikipedia

    en.wikipedia.org/wiki/Surrogate_key

    A surrogate key (or synthetic key, pseudokey, entity identifier, factless key, or technical key [citation needed]) in a database is a unique identifier for either an entity in the modeled world or an object in the database. The surrogate key is not derived from application data, unlike a natural (or business) key. [1]

  7. AltGr key - Wikipedia

    en.wikipedia.org/wiki/AltGr_key

    IBM states that AltGr is an abbreviation for alternate graphic. [3] [4]Sun Microsystems keyboard, which labels the key as Alt Graph. A key labelled with some variation of "Alt Graphic" was on many computer keyboards before the Windows international layouts.

  8. Alt code - Wikipedia

    en.wikipedia.org/wiki/Alt_code

    This did not work for characters not in the Windows Code Page (such as box-drawing characters). The new Alt+0### combination (which prefixes a zero to each Alt code), produces characters from the newer "Windows code pages." [a] For example, Alt+ 0 1 6 3 yields the character £ (symbol for the pound sterling) which is at 163 in CP1252. [2] [b]

  9. Composite key - Wikipedia

    en.wikipedia.org/wiki/Composite_key

    In database design, a composite key is a candidate key that consists of two or more attributes, [1] [2] [3] (table columns) that together uniquely identify an entity occurrence (table row). A compound key is a composite key for which each attribute that makes up the key is a foreign key in its own right.