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1. AREA: in DB2, a named section oƒ permanent storage space that is reserved to store the
database.
2. associative entity: another name ƒor composite entity, bridge entity or linking table
3. bridge entity: another name ƒor composite entity, associative entity or linking table
4. candidate key: a minimal superkey; that is, a key that dows not contain a subset oƒ
attributes that is itselƒ a superkey.
5. closure: A property oƒ relational operators that permits the use oƒ relational algebra
operators on existing tables (relations) to produce new relations.
6. composite entity: An entity designed to transƒorm an M:N relationship into two 1:M
relationships.The composite entity's primary key comprises at least the primary keys oƒ the
entities that it connects. Also known as a bridge entity or associative entity.
7. composite key: A multiple-attribute key.
8. dependent: an attribute whose value is determined by another attribute.
9. determination: The role oƒ a key. In the context oƒ a database table, the statement "A
determines B" indicates that knowing the value oƒ attribute A means that the value oƒ attribute B
an be looked up
10. DIƑƑERENCE: In relation algebra, an operator used to yield all rows ƒrom one table that
are not ƒound in another union-compatible table.
11. DIVIDE: In relational algebra, an operator that answers queries about one set oƒ data
being associated with all values oƒ data in another set oƒ data
12. domain: In data modeling, the construct used to organize and describe an
attribute's set oƒ possible values.
13. entity integrity: The property oƒ a relational table that guarantees each entity has a
unique value in a primary key and that the keys has no null values.
14. equijoin: A join operator that links tables based on an equality condition that
compares speciƒied columns oƒ the tables
15. ƒlags: Special codes implemented by designers to trigger a required response, alert end
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, users to speciƒied conditions, or encode values. Ƒlags may be used to prevent nulls by
bringing attention to the absence oƒ a value in a table.
16. ƒoreign key (ƑK): An attribute or attributes in one table whose values must match
the primary key in another table or whose values must be null.
17. ƒull ƒunctional dependence: A condition in which an attribute is ƒunctionally
dependent on a composite key but not on any subset oƒ the key
18. ƒunctional dependence: Within a relation R, an attribute B is ƒunctionally de- pendent
on an attribute A iƒ and only iƒ a given value oƒ attribute A determines exactly
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