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A candidate key is a minimal superkey, [1] i.e., a superkey that does not contain a smaller one. Therefore, a relation can have multiple candidate keys, each with a different number of attributes. [2] Specific candidate keys are sometimes called primary keys, secondary keys or alternate keys.
A secondary chord is an analytical label for a specific harmonic device that is prevalent in the tonal idiom of Western music beginning in the common practice period: the use of diatonic functions for tonicization. Secondary chords are a type of altered or borrowed chord, chords that are not part of the music piece's key.
V of V in C, four-part harmony Secondary leading-tone chord: vii o 7 /V - V in C major. This may also be considered an altered IV 7 (FACE becomes F ♯ ACE ♭). [1]In music, tonicization is the treatment of a pitch other than the overall tonic (the "home note" of a piece) as a temporary tonic in a composition.
Chromatic harmony may be defined as the use of successive chords that are from two different keys and therefore contain tones represented by the same note symbols but with different accidentals. [35] Four basic techniques produce chromatic harmony under this definition: modal interchange, secondary dominants, melodic tension, and chromatic ...
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.
A foreign key is a set of attributes in a table that refers to the primary key of another table, linking these two tables. In the context of relational databases, a foreign key is subject to an inclusion dependency constraint that the tuples consisting of the foreign key attributes in one relation, R, must also exist in some other (not necessarily distinct) relation, S; furthermore that those ...
A candidate key (or minimal superkey) is a superkey that can't be reduced to a simpler superkey by removing an attribute. [ 3 ] For example, in an employee schema with attributes employeeID , name , job , and departmentID , if employeeID values are unique then employeeID combined with any or all of the other attributes can uniquely identify ...
A sparse index in databases is a file with pairs of keys and pointers for every block in the data file. Every key in this file is associated with a particular pointer to the block in the sorted data file. In clustered indices with duplicate keys, the sparse index points to the lowest search key in each block.