Average Rating 0 out of 5 stars. 0 votes.You must log in to submit a review.Decomposition,”If X → YZ then[…]
Read moreTag: db
Domain contraints,”Attributes must be of the same type and consistent with domain rules. For instance
Average Rating 0 out of 5 stars. 0 votes.You must log in to submit a review.Domain contraints,”Attributes must be of[…]
Read moreMapping Specialization/Generalization,”SUPERTYPE(CommonIdent, CommonAttr1, CommonAttr2)SUBTYPE1(CommonIdent, UniqueAttr1)SUBTYPE2(CommonIdent, UniqueAttr2, UniqueAttr3)As an alternative mapping for total specialization with disjoint relations, you can may consider dropping the supertype and creating tables for each subtype:SUBTYPE1(CommonIdent, CommonAttr1, CommonAttr2, UniqueAttr1)SUBTYPE2(CommonIdent, CommonAttr1, CommonAttr2, UniqueAttr2, UniqueAttr3)SUBTYPE3(CommonIdent, CommonAttr1, CommonAttr2
Average Rating 0 out of 5 stars. 0 votes.You must log in to submit a review.Mapping Specialization/Generalization,”SUPERTYPE(CommonIdent, CommonAttr1, CommonAttr2)SUBTYPE1(CommonIdent, UniqueAttr1)SUBTYPE2(CommonIdent,[…]
Read moreUnion,”If X → Y and X → Z
Average Rating 0 out of 5 stars. 0 votes.You must log in to submit a review.Union,”If X → Y and[…]
Read moreReferential Integrity Constraints,”Every value in a foreign key must have a corresponding
Average Rating 0 out of 5 stars. 0 votes.You must log in to submit a review.Referential Integrity Constraints,”Every value in[…]
Read moret/f? minimum cardinality influences relational schemas
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Read moreT/F? ER’s have foreign keys
Average Rating 0 out of 5 stars. 0 votes.You must log in to submit a review.T/F? ER’s have foreign keys[…]
Read moreMiscellaneous issues 1,”For composite attributes, include only the atomic attributes:CUSTOMER(CustID, Age, Street, City, State, Zip)For a composite attribute that serves as a primary key, you would need to underline all sub-attributes in the relation to clarify this (e.g., for a composite primary key such as FullName, this may break down into: FirstName, MiddleName
Average Rating 0 out of 5 stars. 0 votes.You must log in to submit a review.Miscellaneous issues 1,”For composite attributes,[…]
Read moreT/F? Candidate keys can have multiple columns
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Read moreMiscellaneous issues 2,”For multi-valued attributes, avoid repeating groups (e.g., columns such as Address1, Address2, and Address3) by creating a separate table/schema as you would for M:N relationships:STUDENT(StudentID)STUDENTADDRESS(Address
Average Rating 0 out of 5 stars. 0 votes.You must log in to submit a review.Miscellaneous issues 2,”For multi-valued attributes,[…]
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