A set of possible data values is called
Answer: D
Correct answer: Domain.
A domain is the set of permitted values for an attribute - the integers 0 to 100 for a mark, or a list of valid state codes. Constraining an attribute to its domain is the most basic form of integrity checking a DBMS does.
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A DBMS that combines a DBMS and an application generator is ________ .
Answer: B
Correct answer: Microsoft's Access
Access bundles a DBMS with an application generator: forms, reports, queries and macros in the same file as the data. That is what makes it convenient for a small application and unsuitable for an enterprise one, where the DBMS is a separate server and the application is built independently.
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A database is called "self-describing" because it contains a description of itself.
Answer: A
Correct answer: True
A database stores the definitions of its own structure - tables, columns, data types, keys, indexes - as metadata in system tables, right alongside the user data. That is what “self-describing” means, and it is why a tool can inspect an unfamiliar database without any external documentation.
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The DBMS acts as an interface between what two components of an database system ?
Answer: D
Correct answer: Database Application and Database
The DBMS is the layer between the application and the database. The application issues requests; the DBMS carries them out against the stored data, applying security, integrity and concurrency rules on the way.
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A report generator is used to
Answer: B
Correct answer: Print files on paper
A report generator takes data from the database and formats it for output - headings, grouping, subtotals, page breaks. It is a presentation tool: it does not update, insert or delete anything.
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In a relation
Answer: C
Correct answer: (A) and (B) both are true
A relation is a set of tuples, and two things follow from that. The order of the rows carries no meaning, so a query must sort explicitly if it wants a particular order; and no two rows can be identical, since a set has no duplicates. (SQL tables relax the second rule unless a key or DISTINCT enforces it.)
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In an enterprise-class database system, business users interact directly with database applications, which directly access the database data.
Answer: B
Correct answer: False
There is one more layer. Users interact with applications, applications call the DBMS, and only the DBMS touches the data. Applications never read or write the database files themselves - if they did, there would be no way to enforce security, integrity or concurrency.
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Database is collection of ____.
Answer: B
Correct answer: Data
A database is fundamentally an organised collection of related data, held so that it can be stored, retrieved and managed efficiently. The programs that operate on it are the DBMS and the applications, which are distinct from the database itself.
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Related fields in a database are grouped to form a
Answer: B
Correct answer: Data record.
A record is a group of related fields describing one thing - a customer’s name, address and account number together. Records of the same kind are then grouped into a file, or in relational terms fields are columns, records are rows and the file is a table.
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The natural join is equal to :
Answer: C
Correct answer: Combination of selection and Cartesian product
A natural join is built from the basic operators: form the Cartesian product of the two relations, then select the tuples whose common attributes are equal - and finally project away the duplicated columns. That is why the join is a derived operation rather than a primitive of relational algebra.
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