To download the complete and accurate content document, go to: https://testbankbell.com/download/accounting-information-systems-hall-9th-edition-te st-bank/
1. The database approach to data management is sometimes called the flat file approach.
ANS: F PTS: 1
2. The database management system provides a controlled environment for accessing the database.
ANS: T PTS: 1
3. To the user, data processing procedures for routine transactions, such as entering sales orders, appear to be identical in the database environment and in the traditional environment.
ANS: T PTS: 1
4. An important feature associated with the traditional approach to data management is the ability to produce ad hoc reports.
ANS: F PTS: 1
5. The data definition language is used to insert special database commands into application programs.
ANS: F PTS: 1
6. There is more than one conceptual view of the database.
ANS: F PTS: 1
7. In the database method of data management, access authority is maintained by systems programming.
ANS: F PTS: 1
8. The physical database is an abstract representation of the database.
ANS: F PTS: 1
9. A customer name and an unpaid balance is an example of a one-to-many relationship.
ANS: F PTS: 1
10. In the relational model, a data element is called a relation.
ANS: F PTS: 1
11. The normalization process involves identifying and removing structural dependencies from the tables being modeled.
ANS: T PTS: 1
© 2015 Cengage Learning. All rights reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.
12. Under the database approach, data is viewed as proprietary or owned by users.
ANS: F PTS: 1
13. The data dictionary describes all of the data elements in the database.
ANS: T PTS: 1
14. A join builds a new table by creating links.
ANS: F PTS: 1
15. The deletion anomaly is the least important of the problems affecting unnormalized databases.
ANS: F PTS: 1
16. A deadlock is a phenomenon that prevents the processing of transactions.
ANS: T PTS: 1
17. Timestamping is a control that is used to ensure database partitioning.
ANS: F PTS: 1
18. A lockout is a software control that prevents multiple users from simultaneous access to data.
ANS: T PTS: 1
19. Task-data dependency is directly related to data redundancy.
ANS: F PTS: 1
20. An entity is any physical thing about which the organization wishes to capture data.
ANS: F PTS: 1
21. An ER diagram is a graphical representation of a data model.
ANS: T PTS: 1
22. The term occurrence is used to describe the number of attributes or fields pertaining to a specific entity.
ANS: F PTS: 1
23. Cardinality describes the number of possible occurrences in one table that are associated with a single occurrence in a related table.
ANS: T PTS: 1
© 2015 Cengage Learning. All rights reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.
24. Foreign keys physically connect logically related tables to achieve the associates described in the data model.
ANS: T PTS: 1
25. Improperly normalized databases are associated with three types of anomalies: the update anomaly, the insertion anomaly, and the deletion anomaly.
ANS: T PTS: 1
1. Task-data dependency is
a. failure to update the files of all users affected by a change
b. another term for data redundancy
c. user’s inability to obtain additional information as needs change
d. none of the above
ANS: C PTS: 1
2. The task of searching the database to locate a stored record for processing is called
a. data deletion
b. data storage
c. data attribution
d. data retrieval
ANS: D PTS: 1
3. Which of the following is not a problem usually associated with the flat-file approach to data management?
a. data redundancy
b. restricting access to data to the primary user
c. data storage
d. currency of information
ANS: B PTS: 1
4. Which characteristic is associated with the database approach to data management?
a. data sharing
b. multiple storage procedures
c. data redundancy
d. excessive storage costs
ANS: A PTS: 1
5. Which characteristic is not associated with the database approach to data management?
a. the ability to process data without the help of a programmer
b. the ability to control access to the data
c. constant production of backups
d. the inability to determine what data is available
ANS: D PTS: 1
6. The textbook refers to four interrelated components of the database concept. Which of the following is not one of the components?
a. the database management system
b. the database administrator
c. the physical database
d. the conceptual database
ANS: D PTS: 1
7. The formal name for a row in the physical database table is
a. attribute
b. schema
c. tuple
d. link
ANS: C PTS: 1
8. A description of the physical arrangement of records in the database is
a. the internal view
b. the conceptual view
c. the subschema
d. the external view
ANS: A PTS: 1
9. Which of the following may provide many distinct views of the database?
a. the schema
b. the internal view
c. the user view
d. the conceptual view
ANS: C PTS: 1
10. Users access the database
a. by direct query
b. by developing operating software
c. by constantly interacting with systems programmers
d. all of the above
ANS: A PTS: 1
11. The data definition language
a. identifies, for the database management system, the names and relationships of all data elements, records, and files that comprise the database
b. inserts database commands into application programs to enable standard programs to interact with and manipulate the database
c. permits users to process data in the database without the need for conventional programs
d. describes every data element in the database
ANS: A PTS: 1
12. The data manipulation language
a. defines the database to the database management system
b. transfers data to the buffer area for manipulation
c. enables application programs to interact with and manipulate the database
d. describes every data element in the database
ANS: C PTS: 1
13. Which statement is not correct? A query language like SQL
a. is written in a fourth-generation language
b. requires user familiarity with COBOL
c. allows users to retrieve and modify data
d. reduces reliance on programmers
ANS: B PTS: 1
14. Which duty is not the responsibility of the database administrator?
a. to develop and maintain the data dictionary
b. to implement security controls
c. to design application programs
d. to design the subschema
ANS: C PTS: 1
15. In a hierarchical model
a. links between related records are implicit
b. the way to access data is by following a predefined data path
c. an owner (parent) record may own just one member (child) record
d. a member (child) record may have more than one owner (parent)
ANS: B PTS: 1
16. Which term is not associated with the relational database model?
a. tuple
b. attribute
c. collision
d. relation
ANS: C PTS: 1
17. In the relational database model
a. relationships are explicit
b. the user perceives that files are linked using pointers
c. data is represented on two-dimensional tables
d. data is represented as a tree structure
ANS: C PTS: 1
18. In the relational database model all of the following are true except
a. data is presented to users as tables
b. data can be extracted from specified rows from specified tables
c. a new table can be built by joining two tables
d. only one-to-many relationships can be supported
ANS: D PTS: 1
19. Properly designed physical database tables must
a. have a unique name for each column that may not be repeated in other tables
b. confirm to the rules of normalization
c. Both a. and b.
d. Neither a. nor b.
ANS: B PTS: 1
20. The update anomaly in unnormalized databases
a. occurs because of data redundancy
b. complicates adding records to the database
c. may result in the loss of important data
d. often results in excessive record insertions
ANS: A PTS: 1
21. The most serious problem with unnormalized databases is the
a. update anomaly
b. insertion anomaly
c. deletion anomaly
d. none of the above
ANS: C PTS: 1
22. The deletion anomaly in unnormalized databases
a. is easily detected by users
b. may result in the loss of important data
c. complicates adding records to the database
d. requires the user to perform excessive updates
ANS: B PTS: 1
23. Which statement is correct?
a. in a normalized database, data about vendors occur in several locations
b. the accountant is responsible for database normalization
c. in a normalized database, deletion of a key record could result in the destruction of the audit trail
d. connections between M:M tables are provided by a link table
ANS: D PTS: 1
24. Which of the following is not a common form of conceptual database model?
a. hierarchical
b. network
c. sequential
d. relational
ANS: C PTS: 1
25. Which of the following is a relational algebra function?
a. restrict
b. project
c. join
d. all are relational algebra functions
ANS: D PTS: 1
26. Which statement is false?
a. The DBMS is special software that is programmed to know which data elements each user is authorized to access.
b. User programs send requests for data to the DBMS.
c. During processing, the DBMS periodically makes backup copies of the physical database.
d. The DBMS does not control access to the database.
ANS: D PTS: 1
27. All of the following are elements of the DBMS which facilitate user access to the database except
a. query language
b. data access language
c. data manipulation language
d. data definition language
ANS: B PTS: 1
28. Which of the following is a level of the database that is defined by the data definition language?
a. user view
b. schema
c. internal view
d. all are levels or views of the database
ANS: D PTS: 1
29. An example of a distributed database is
a. partitioned database
b. centralized database
c. networked database
d. all are examples of distributed databases
ANS: A PTS: 1
30. Data currency is preserved in a centralized database by
a. partitioning the database
b. using a lockout procedure
c. replicating the database
d. implementing concurrency controls
ANS: B PTS: 1
31. Which procedure will prevent two end users from accessing the same data element at the same time?
a. data redundancy
b. data replication
c. data lockout
d. none of the above
ANS: C PTS: 1
32. The advantages of a partitioned database include all of the following except
a. user control is enhanced
b. data transmission volume is increased
c. response time is improved
d. risk of destruction of entire database is reduced
ANS: B PTS: 1
33. A replicated database is appropriate when
a. there is minimal data sharing among information processing units
b. there exists a high degree of data sharing and no primary user
c. there is no risk of the deadlock phenomenon
d. most data sharing consists of read-write transactions
ANS: B PTS: 1
34. What control maintains complete, current, and consistent data at all information processing units?
a. deadlock control
b. replication control
c. concurrency control
d. gateway control
ANS: C PTS: 1
35. Data concurrency
a. is a security issue in partitioned databases
b. is implemented using timestamping
c. may result in data lockout
d. occurs when a deadlock is triggered
ANS: B PTS: 1
36. Entities are
a. nouns that are depicted by rectangles on an entity relationship diagram
b. data that describe the characteristics of properties of resources
c. associations among elements
d. sets of data needed to make a decision
ANS: A PTS: 1
37. A user view
a. presents the physical arrangement of records in a database for a particular user
b. is the logical abstract structure of the database
c. specifies the relationship of data elements in the database
d. defines how a particular user sees the database
ANS: D PTS: 1
38. All of the following are advantages of a partitioned database except
a. increased user control by having the data stored locally
b. deadlocks are eliminated
c. transaction processing response time is improved
d. partitioning can reduce losses in case of disaster
ANS: B PTS: 1
39. Each of the following is a relational algebra function except
a. join
b. project
c. link
d. restrict
ANS: C PTS: 1
40. A table is in first normal form when it is
a. free of repeating group data
b. free of transitive dependencies
c. free of partial dependencies
d. free of update anomalies
e. none of the above
ANS: A PTS: 1
41. A table is in second normal form when it is
a. free of repeating group data
b. free of transitive dependencies
c. free of partial dependencies
d. free of insert anomalies
e. none of the above
ANS: C PTS: 1
42. A table is in third normal form when it is
a. free of repeating group data
b. free of transitive dependencies
c. free of partial dependencies
d. free of deletion anomalies
e. none of the above
ANS: B PTS: 1
Use the following words to complete the sentences.
database administrator data dictionary data redundancy index sequential access method query language schema sequential structure subschema
1. _________________________ occurs when a specific file is reproduced for each user who needs access to the file.
ANS: data redundancy
PTS: 1
2. The conceptual view of the database is often called ____________________.
ANS: schema
PTS: 1
3. The ____________________ allows users to retrieve and modify data easily.
ANS: query language
PTS: 1
4. The __________________________ authorizes access to the database.
ANS: database administrator
PTS: 1
5. The __________________________ describes every data element in the database.
ANS: data dictionary
PTS: 1
6. What are the three data management problems caused by data redundancy?
ANS: data storage, date updating and currency of information
PTS: 1
7. What is the relationship between a database table and a user view?
ANS:
User views are derived database tables. A single table may contribute data to several different views On the other hand, simple views may be constructed from a single table.
PTS: 1
8. How does the database approach solve the problem of data redundancy?
ANS:
Data redundancy is not a problem with the database approach because individual data elements need to be stored only once yet be available to multiple users.
PTS: 1
9. Explain how linkages between relational tables are accomplished.
ANS:
Logically related tables need to be physically connected to achieve the associations described in the data model This is accomplished by using foreign keys. The degree of cardinality between the related tables determines the method used for assigning foreign keys.
Where a 1:M (or 1:0,M) association exists, the primary key of the 1 side is embedded in the table of the M side.
To represent the M:M association between tables, a link table needs to be created that has a combined (composite) key consisting of the primary keys of two related tables.
PTS: 1
©
10. Explain the basic results that come from the restrict, project, and join functions.
ANS:
A restrict extracts selected rows from a table–records that satisfy prescribed conditions–to create a new table.
A project extracts selected attributes (columns) from a table to create a new table.
A join builds a new table, from two existing tables, by matching rows on a value of a common attribute.
PTS: 1
11. Explain the purpose of an ER diagram in database design.
ANS:
The entity relationship (ER) diagram is the graphical representation technique used to depict a data model. Each entity in a ER diagram is named in the singular noun form such as Customer rather than Customers. The labeled line connecting two entities describes the nature of the association between them. This association is represented with a verb such as shipped, requests, or receives. The ER diagram also represents cardinality (the degree of association between two entities). Four basic forms of cardinality are possible: zero or one (0,1), one and only one (1,1), zero or many (0,M), and one or many (1,M). These are combined to represent logical associations between entities such as 1:1, 1:0,M, and M:M.
PTS: 1
12. What are two types of distributed databases?
ANS: Partitioned and replicated databases.
PTS: 1
13. Describe an environment in which a firm should use a partitioned database.
ANS:
A partitioned database approach works best in organizations that require minimal data sharing among its information processing units and when a primary user of the data can be identified.
PTS: 1
14. Explain how to link tables in (1:1) association. Why may this be different in a (1:0,1) association?
ANS:
Where a true 1:1 association exists between tables, either (or both) primary keys may be embedded as foreign keys in the related table. On the other hand, when the lower cardinality value is zero (1:0,1) a more efficient table structure can be achieved by placing the one-side (1:) table’s primary key in the zero-or-one (:0,1) table as a foreign key. Assume that a company has 1000 employees but only 100 of them are sales staff. Assume also that each sales person is assigned a company car. Therefore, every occurrence in the Employee entity is associated with either zero or one occurrence in the Company Car entity. If we assigned the Company Car (:0,1) side primary to the Employee (:1) table as a foreign key then most of the foreign will have null (blank) values. While this approach would work, it could cause some technical problems during table searches. Correctly applying the key-assignment rule solves this problem because all Company Car records will have an employee assigned and no null values will occur.
PTS: 1
15. Why are the hierarchical and network models called navigational databases?
ANS:
These are called navigational models because traversing or searching them requires following a predefined path which is established through explicit linkages between related records.
PTS: 1
16. What is view integration?
ANS:
A modern company uses hundreds or thousands of views and associated tables. Combining the data needs of all users into a single schema or enterprise-wide view is called view integration
PTS: 1
17. What is a database lockout?
ANS:
To achieve data currency, simultaneous access to individual data elements by multiple sites needs to be prevented. The solution to this problem is to use a database lockout, which is a software control that prevents multiple simultaneous accesses to data.
PTS: 1
18. What is the partitioned database approach and what are its advantages?
ANS:
The partitioned database approach splits the central database into segments or partitions that are distributed to their primary users. The advantages of this approach are:
Storing data at local sites increases users’ control. Permitting local access to data and reducing the volume of data that must be transmitted between sites improves transaction processing response time.
Partitioned databases can reduce the potential for disaster. By having data located at several sites, the loss of a single site cannot terminate all data processing by the organization.
PTS: 1
19. What is a replicated database and what are the advantages of this approach?
ANS:
The entire database is replicated at each distributed site.
Replicated databases are effective in companies where there exists a high degree of data sharing but no primary user. Since common data are replicated at each site, the data traffic between sites is reduced considerably.
PTS: 1
20. What is repeating group data?
ANS:
Repeating group data is the existence of multiple values for a particular attribute in a specific record.
PTS: 1
21. What is a partial dependency?
ANS:
A partial dependency occurs when one or more nonkey attributes are dependent on (defined by) only part of the primary key, rather than the whole key. This can occur only in tables that have composite (two or more attribute) primary keys.
PTS: 1
22. What is a transitive dependency?
ANS:
A transitive dependency occurs in a table where nonkey attributes are dependent on another nonkey attribute and independent of the table’s primary key.
PTS: 1
23. What is the update anomaly?
ANS:
The update anomaly results from data redundancy in an unnormalized table. The data attributes pertaining to particular entity (for example Vendor Name, Address, and Tele Num) are repeated in every record in every record pertaining to the vendor. Any change in the supplier’s name, address, or telephone number must then be made to each of these records. This causes an update problem that results in excessive overhead costs.
PTS: 1
24. What is the insertion anomaly?
ANS: When a table is unnormalized, certain types of new records cannot be added to it.
PTS: 1
25. When is a table in third normal form (3NF)?
ANS:
A table is in third normal form when it meets the two conditions below:
1. All nonkey (data) attributes in the table are dependent on (defined by) the primary key.
2. All nonkey attributes are independent of the other nonkey attributes.
PTS: 1
1. What is the normal cardinality between a Customer entity and a Sales order entity? What does it signify? Why is it the only logical cardinality?
ANS:
The normal cardinality is 1:M which signifies that one customer may play many orders during a sales period. The cardinality would never be 1:1. That would mean that each customer was restricted to a signal sale.
PTS: 1
2. Explain the three types of anomalies associated with database tables that have not been normalized.
ANS:
The update anomaly is the result of data redundancy. If a data element is stored in more than one place, it must be updated in all places. If this does not happen, the data are inconsistent.
The insertion anomaly occurs when too data is stored together, such as when vendor information is only stored with specific inventory items. Until items are purchased from a given vendor, the vendor cannot be added to the database.
The deletion anomaly involves the unintentional deletion of data from a table. If a vendor supplies only one item, and the firm discontinues that item, all information on the vendor is lost when vendor information is only stored with specific inventory items.
PTS: 1
3. What are the four elements of the database approach? Explain the role of each.
ANS:
Users are the individuals in the organization who access the data in the database. This may happen via user programs or by direct query.
The database management system is a set of programs that control access to the database and that manage the data resource through program development, backup and recovery functions, usage reporting, and access authorization.
The database administrator is a function (which may involve part of one individual’s duties or an entire department) which manages the database resources through database planning, design, implementation, operation and maintenance, and growth and change.
The physical database is the lowest level of the database and consists of magnetic spots on magnetic media. The other levels of the database are abstract representations of the physical level. At the physical level, the database is a collection of records and files.
PTS: 1
4. Explain the three views of a database.
ANS:
The unique internal view of the database is the physical arrangement of records which describes the structure of data records, the linkages between files, and the physical arrangement and sequence of records in the file.
The unique conceptual view (or schema) represents the database logically and abstractly. This view allows users’ programs to call for data without knowing or needing to specify how the data are arranged or where the data reside in the physical database.
The many user views (or subschema) define the portion of a database that an individual user is authorized to access. To the user, the user view is the database.
PTS: 1
5. Explain a database lockout and the deadlock phenomenon. Contrast that to concurrency control and the timestamping technique. Describe the importance of these items in relation to database integrity.
ANS:
In a centralized database, a database lockout is used to ensure data currency. It is a software control that prevents multiple simultaneous access to data. Upon receiving a data access request, the central site DBMS places a lock on the requested data to prevent additional access until the lock is removed.
In a distributed environment it is possible that multiple sites will lock each other out, preventing each from processing its transactions. This results in a deadlock because there is mutual exclusion to data and the transactions are in a wait state until the locks are removed. A deadlock is a permanent condition that must be resolved by special software that analyzes each deadlock to determine the best solution.
© 2015 Cengage Learning. All rights reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.
In a replicated database, a large volume of data flows between sites, and temporary inconsistencies in the database may occur. Database concurrency is the presence of complete and accurate data at all remote sites. A commonly used method for concurrency control is to serialize and timestamp transactions that are in conflict
Both database lockouts and concurrency controls are designed to ensure that the transactions are completely processed and that all transactions are accurately reflected in the firm’s databases. Failure to implement these controls can result in transactions being lost, being partially processed, or with inconsistent databases.
PTS: 1
6. How is a database deadlock usually resolved? What are factors that influence the decision made regarding the transactions?
ANS:
Resolving a deadlock usually involves sacrificing one or more transactions which must be terminated to complete the processing of other transactions in the deadlock. Preempted transactions must be reinitiated. Some of the factors to consider in the transaction decision are: (1) the resources currently invested in the transaction, (2) the transaction’s stage of completion, and (3) the number of deadlocks associated with the transaction.
PTS: 1
7. In a distributed data processing system, a database can be centralized or distributed. Explain each.
ANS:
When the database is centralized, the entire database is stored at a central site which processes requests from users at remote locations. The central site performs the functions of a file manager that services the data needs of the remote users.
Distributed databases can be partitioned replicated. The partitioned approach splits the central database into segments or partitions that are distributed to their primary users. When the database is partitioned, users have more control over data stored at local sites, transaction processing time is improved, and the potential of data loss is reduced. When the database is replicated, the entire database is stored at multiple locations. Replicated databases are effective where there is a high degree of data sharing but no primary user. Data traffic between sites is reduced considerably. The primary justification for a replicated database is to support read-only queries.
PTS: 1
8. What are the four characteristics of a properly designed database table?
ANS:
1. The value of at least one attribute in each tuple (row) must be unique. This is the primary key.
2. All attribute values in any column must be of the same class.
3. Each column in a given table must be uniquely named. Different tables may contain columns with the same name.
4. Tables must conform to the rules of normalization – free from structural dependencies, partial dependencies and transitive dependencies.
PTS: 1
9. What are the problems with the flat-file approach? How does the database approach solve them?
ANS:
Data redundancy causes significant data management problems in three areas: data storage, data updating, and currency of information. Data storage is a problem because if multiple users need the data, it must be collected and stored multiple times at multiple costs. When multiple users hold the same information, changes must be updated in all locations or data inconsistency results. Failure to update all occurrence of a data item can affect the currency of the information. If update messages are not properly disseminated, some users may not record the change and will perform their duties and make decisions based on outdated data.
Another problem is task-data dependency which is the user’s inability to obtain additional information as needs change.
With a database system, these problems are solved. There is no data redundancy since a data item is stored only once. Hence changes require only a single update, thus leading to current value. A common database is shared by all users, eliminating the problem of task-data dependency.
PTS: 1
10. What typical features are provided by a database management system (DBMS)?
ANS:
1. Program development which permits both programmers and end users to create applications to access the database.
2. Backup and recovery is built in, reducing the likelihood of total data destruction.
3. Database usage reporting captures statistics on what data is being used, when and by whom. The database administrator uses this information to assign user authorization and maintain the database.
4. Database access to authorized users is the most important feature of a DBMS.
PTS: 1
11. Define repeating groups, partial dependencies and transitive dependencies and discuss how they are dealt with in the process of normalizing tables.
ANS:
Repeating group data occurs when multiple values for a particular attribute exist in a specific tuple (row). To avoid data redundancy, repeating group data needs to be removed from the table and placed in a separate table.
A partial dependency occurs when one or more nonkey attributes are dependent on (defined by) only part of the primary key rather than the whole key. This can only occur in tables that have composite (two or more attributes) primary keys. This is resolved by splitting the table in two.
A transitive dependency occurs in a table where nonkey attributes are dependent on another nonkey attribute and independent of the table’s primary key. This is resolved by splitting out the independent data and placing it in a new table.
PTS: 1
12. List the steps involved in creating a relational database using a top-down approach.
ANS:
1. Identify the views to be modeled.
2. Normalize the data model and add primary keys.
3. Determine cardinalities and add foreign keys.
4. Construct the physical database.
5. Prepare the physical user views.
PTS: 1
13. Discuss the accountant’s role in data modeling and potential problems caused by anomalies.
ANS:
Most accountants will not be directly responsible for normalizing an organization’s databases, but they should have an understanding of the process and be able to determine whether financial data are properly normalized to avoid anomalies. The conduct of many financial audit procedures involves accessing data stored in normalized tables. An organization’s financial database may consist of thousands of normalized tables and navigating the network requires an understanding of data structures.
The update anomaly can generate conflicting and/or obsolete database values in accounts, the insertion anomaly can result in unrecorded transactions and incomplete audit trails, and the deletion anomaly can cause the loss of accounting records and destruction of audit trails.
PTS: 1
14 Discuss the hierarchical database model. What limitation(s) of the hierarchical database model are solved by the network database model?
ANS:
The earliest DBMS were based on the hierarchical data model. This was a popular approach to data representation because it reflected many aspects of an organization that are hierarchical in relationship. It was an efficient data processing tool for highly structured problems. The hierarchical model is constructed of sets of files. Each set contains a parent and a child. Files at the same level with the same parent are called siblings.
The hierarchical data model is a navigational database because traversing it requires following a predefined path, established through pointers.
A parent record may have one or more child records, but no child record can have more than one parent which is restrictive and limits the usefulness of the model. Many firms need a view that permits multiple parents. That limitation is solved by the network database model which allows a child record to have multiple parents.
PTS: 1