Relational Database Model Quiz

A relational model defines a database as a collection of relations represented as two-dimensional tables with distinct columns and rows.

A tuple is a row in a relational table that represents a single record, consisting of values for each attribute.

Domains define the set of permissible values for each attribute in a table and help maintain data integrity within the database.

<p>Relations must be homogeneous in columns, contain distinct rows, and have unordered rows and columns with distinct names.</p> Signup and view all the answers

<p>A relational schema specifies a relation's name, its attributes, and the domain for each attribute.</p> Signup and view all the answers

<p>First normal form (1NF) requires that all values in a table must be atomic, meaning each column must contain only indivisible values.</p> Signup and view all the answers

<p>Functional dependency describes a relationship where one attribute uniquely determines another attribute within a relation.</p> Signup and view all the answers

<p>Distinct rows ensure that each record represents a unique entity, avoiding redundancy and promoting data integrity.</p> Signup and view all the answers

<p>Rule 0 states that a database must exclusively use its relational facilities to manage data to be considered relational.</p> Signup and view all the answers

<p>Rule 1 states that all information in an RDBMS must be represented as values in tables, including metadata like table names and column data types.</p> Signup and view all the answers

<p>According to Rule 2, a unique piece of data can be accessed using the table name, primary key (row), and attribute (column).</p> Signup and view all the answers

<p>Rule 3 states that NULL values must be uniformly treated, as a NULL can indicate missing, unknown, or inapplicable data.</p> Signup and view all the answers

<p>Codd's rules provide a set of principles that guide the creation, management, and operation of relational databases to ensure data integrity and accessibility.</p> Signup and view all the answers

<p>Rule 1 contributes by ensuring all data is stored in a tabular format, thus maintaining a consistent and unified structure for data representation.</p> Signup and view all the answers

<p>The primary key is vital because it uniquely identifies each row in a table, ensuring that every data element can be accessed reliably.</p> Signup and view all the answers

<p>If a DBMS does not follow Codd's rules, it may not function as a true relational database, leading to data integrity issues and challenges in data accessibility.</p> Signup and view all the answers

<p>It refers to a situation where non-primary-key attributes are fully dependent on the entire primary key and not just a part of it.</p> Signup and view all the answers

<p>The transition to 2NF ensures that databases are free from partial dependencies, which helps eliminate redundancy.</p> Signup and view all the answers

<p>One non-primary-key attribute is 'rent', and another is 'oName'.</p> Signup and view all the answers

<p>'CR' likely signifies 'Client Rental', indicating it relates to rental clients.</p> Signup and view all the answers

<p>'rentFinish' indicates the end date of the rental period, essential for managing lease agreements.</p> Signup and view all the answers

<p>The rental rates vary, indicating differences in property value or tenant agreements.</p> Signup and view all the answers

<p>It's important to prevent anomalies such as update and deletion anomalies, ensuring data integrity.</p> Signup and view all the answers

<p>It indicates that a client can have multiple rental agreements over time.</p> Signup and view all the answers

<p>The cost is calculated as the height traversed in the index to locate the block pointer plus one for the block of the primary key that is transferred for access.</p> Signup and view all the answers

<p>The three algorithms are nested-loop join, block nested-loop join, and indexed nested-loop join.</p> Signup and view all the answers

<p>A hash key retrieval retrieves a single record directly, while a primary index scan may require traversing multiple levels in the index.</p> Signup and view all the answers

<p>Search algorithms are limited because the selection condition must be on the search-key of the index.</p> Signup and view all the answers

<p>The additional cost is the lock transfer needed for finding the hash target plus one.</p> Signup and view all the answers

<p>Materialization stores results on disk, while pipelining passes tuples to parent operations during execution.</p> Signup and view all the answers

<p>Disk transfer is slow and relatively easy to estimate, leading to significant time costs in query execution.</p> Signup and view all the answers

<p>The cost is defined as the number of blocks in the database, denoted as Nb.</p> Signup and view all the answers

<p>The cost is approximately Nb/2, as on average half the file needs to be traversed.</p> Signup and view all the answers

<p>Binary search is applicable when the selection involves an equality comparison on an ordered attribute.</p> Signup and view all the answers

<p>The cost is estimated as the cost of locating the first tuple through binary search plus the sequence of other blocks that satisfy the condition.</p> Signup and view all the answers

<p>The two values are log2(Nb) and the average number of tuples with the same value divided by the blocking factor.</p> Signup and view all the answers

<p>Factors like the number of seeks, average seek cost, and the number of blocks read and written are considered.</p> Signup and view all the answers

<p>Transitive dependency occurs when a non-prime attribute is functionally dependent on another non-prime attribute, via a prime attribute.</p> Signup and view all the answers

<p>No, a relation cannot be in 3NF if it has transitive dependencies between non-prime attributes.</p> Signup and view all the answers

<p>The transitive dependency is that rno -&gt; zip and zip -&gt; city leads to rno -&gt; city.</p> Signup and view all the answers

<p>The relation would be converted to Stud_info {rno, name, marks, dob, zip} and Zip_city {zip, city}.</p> Signup and view all the answers

<p>It must be in Second Normal Form (2NF) and have no transitive dependencies of non-prime attributes on candidate keys.</p> Signup and view all the answers

<p>The functional dependency is clientNo -&gt; cName, where clientNo is the primary key.</p> Signup and view all the answers

<p>No, a relation must be in 3NF in order to potentially qualify for BCNF.</p> Signup and view all the answers

<p>A candidate key is a minimal set of attributes that can uniquely identify a record in a relation.</p> Signup and view all the answers

<p>The primary key for the Rental relation is the combination of clientNo, propertyNo, rentStart, and rentFinish.</p> Signup and view all the answers

<p>In 3NF, for any non-trivial functional dependency X -&gt; A, either X must be a super key or A must be a prime attribute.</p> Signup and view all the answers

<p>propertyNo is a primary key that functionally determines pAddress, rent, ownerNo, and oName.</p> Signup and view all the answers

<p>A super key is a set of one or more attributes that, when taken collectively, can uniquely identify a tuple in a relation.</p> Signup and view all the answers

<p>It is likely not in BCNF, as BCNF requires the left-hand side of every dependency to be a candidate key.</p> Signup and view all the answers

<p>Transitive dependencies must be removed by placing the dependent attributes in a new relation along with a copy of the determinant.</p> Signup and view all the answers

<p>This is a transitive dependency since ownerNo determines oName within the PropertyOwner relation.</p> Signup and view all the answers

<p>Converting to 3NF eliminates redundancy and prevents issues like update anomalies within the database.</p> Signup and view all the answers