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Example of a finished French duplicate game. Eight players have won the individual duplicate world title more than once: Marc Selis Belgium (1974, 1976) Benjamin Hannuna France (1979, 1984) Michel Duguet France (1982, 1983, 1985, 1987, 1988) Christian Pierre Belgium (1991, 1992, 1994, 1996, 1998) Emmanuel Rivalan France (1993, 1999)
Additionally, unless the list is regularly pruned to remove elements with duplicate keys, multiple values associated with the same key will increase the size of the list, and thus the time to search, without providing any compensatory advantage. One advantage of association lists is that a new element can be added in constant time.
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 doesn't contain a smaller one. Therefore ...
For referential integrity to hold in a relational database, any column in a base table that is declared a foreign key can only contain either null values or values from a parent table's primary key or a candidate key. [2] In other words, when a foreign key value is used it must reference a valid, existing primary key in the parent table.
This is a comparison of English dictionaries, which are dictionaries about the language of English.The dictionaries listed here are categorized into "full-size" dictionaries (which extensively cover the language, and are targeted to native speakers), "collegiate" (which are smaller, and often contain other biographical or geographical information useful to college students), and "learner's ...
All the candidate keys of a relation can uniquely identify the records of the relation, but only one of them is used as the primary key of the relation. The remaining candidate keys are called unique keys because they can uniquely identify a record in a relation. Unique keys can consist of multiple columns. Unique keys are also called alternate ...
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This is a good quality dictionary; however, even the best dictionaries have their limits as sources for an encyclopedia article in Wikipedia. Wikipedia generally prefers secondary sources in support of articles. It has a policy distinguishing among primary, secondary, and tertiary sources.