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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]
This list includes SQL reserved words – aka SQL reserved keywords, [1] [2] as the SQL:2023 specifies and some RDBMSs have added. Reserved words in SQL and related products In SQL:2023 [ 3 ]
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 ...
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 ...
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 ...
Next to this name, a character can have one or more formal (normative) alias names. Such an alias name also follows the rules of a name: characters used (A-Z, -, 0-9, <space>) and not used (a-z, %, $, etc.). Alias names are also unique in the full name set (that is, all names and alias names are all unique in their combined set).
Final name Notes Ref SQLNT SQL Server 4.21 [citation needed] SQL95 SQL Server 6.0 [citation needed] Hydra SQL Server 6.5 [citation needed] Sphinx SQL Server 7.0 [128] Plato OLAP Services 7.0 "OLAP Services" was later renamed Microsoft Analysis Services [129] Shiloh SQL Server 2000 Version 8 [citation needed] Rosetta Reporting Services in SQL ...
In the relational data model a superkey is any set of attributes that uniquely identifies each tuple of a relation. [1] [2] Because superkey values are unique, tuples with the same superkey value must also have the same non-key attribute values.