A logical schema
Answer: A
Correct answer: Is the entire database.
The logical (conceptual) schema is the complete description of the whole database - every table, column, key and constraint - as one community view. It is distinct from the internal schema, which says how the data sits on disk, and from the external schemas or subschemas, each of which shows one application its own slice.
Please log in or register to report this question.
The purpose of a database is to help people stop using spreadsheets.
Answer: B
Correct answer: False
The purpose of a database is to keep track of things - particularly things with relationships among them, which a spreadsheet handles badly. Spreadsheets remain the right tool for calculation and analysis; the question is what kind of problem you have, not which tool to abolish.
Please log in or register to report this question.
An application where only one user accesses the database at a given time is an example of a(n) ________ .
Answer: A
Correct answer: single-user database application
By definition: one user at a time means a single-user application - a personal address book or a small Access database. The distinction matters because concurrency control, locking and much of the administrative machinery exist only for the multi-user case.
Please log in or register to report this question.
On which structure is the hierarchical model based?
Answer: A
Correct answer: Tree
The hierarchical model is based on the tree: one root, and every other record type with exactly one parent. Its successor, the network model, allows a record to have several parents and so is based on a graph.
Please log in or register to report this question.
A database design may be based on existing data.
Answer: A
Correct answer: True
A design may well start from data that already exists - spreadsheets, legacy files, another system’s tables. The process is different from designing from requirements: the existing structures have to be analysed and normalised rather than derived, and this is where much real database work begins.
Please log in or register to report this question.
In E-R diagram generalization is represented by
Answer: D
Correct answer: Triangle
Generalisation and its inverse, specialisation, are drawn as a triangle labelled ISA, connecting the general entity set above to the specialised ones below. An ellipse is an attribute, a dashed ellipse a derived one, and a rectangle an entity set.
Please log in or register to report this question.
The following are functions of a DBMS except ________ .
Answer: A
Correct answer: creating and processing forms
A DBMS creates databases, processes data and provides the tools to administer them - backup, security, concurrency. Forms belong to the application, not to the DBMS: they are the user interface built on top of it. (Products such as Access blur the line by bundling both, which is what makes this question worth asking.)
Please log in or register to report this question.
Cross Product is a:
Answer: C
Correct answer: Binary Operator
The Cartesian product takes two relations and returns one, so it is a binary operator - as are union, difference, intersection and join. Selection and projection are unary, taking a single relation.
Please log in or register to report this question.
In __________ data can be stored in structured manner.
Answer: C
Correct answer: Database
A database stores data in a structured way: organised into tables of typed columns, with keys and defined relationships between them. The CPU and ALU are processing hardware and store nothing of the kind.
Please log in or register to report this question.
What is a relationship called when it is maintained between two entities?
Answer: B
Correct answer: Binary
A relationship’s degree is the number of entity types it connects: binary for two, unary (recursive) for one entity type related to itself, ternary for three. Binary relationships are much the most common.
Please log in or register to report this question.
