Database - Data Models into Database Designs - Discussion
Discussion Forum : Data Models into Database Designs - General Questions (Q.No. 16)
16.
Which constraint requires that the binary relationship indicate all combinations that must appear in the ternary relationship?
Discussion:
2 comments Page 1 of 1.
Sravs said:
9 years ago
@Manoj.
Then what's difference between must & must not?
Then what's difference between must & must not?
MANOJ KUMAR said:
1 decade ago
Ternary and higher-order relationships can be treated as combinations of binary relationships.
There are three types of binary constraints: MUST, MUST NOT, and MUST COVER.
MUST NOT constraint: the binary relationship indicates combinations that are not allowed to occur in the ternary relationship.
MUST COVER constraint: the binary relationship indicates all combinations that must appear in the ternary relationship.
There are three types of binary constraints: MUST, MUST NOT, and MUST COVER.
MUST NOT constraint: the binary relationship indicates combinations that are not allowed to occur in the ternary relationship.
MUST COVER constraint: the binary relationship indicates all combinations that must appear in the ternary relationship.
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