database ch 1&2 quiz

What WOULDN'T be needed in a standalone PC DBMS? Provide justification.

-Concurrency control services: only single user -Authorization services: only single user, but may be needed if different individuals are to use the DBMS at different times -Utility Services - limited in scope -Support for data communication - only in standalone system

What are the types of facility you would expect to be provided in a multi-user DBMS?

-Data storage, retrieval, and update -a user-accessible catalog -transaction support -recovery services -authorization services -integrity services

What are views?

These present only a subset of the database that is of particular interest to the end user. Views can be customized, such as hiding certain aspects from a particular group of people

Discuss the advantages and disadvantages of database management systems.

advantages: control of data redundancy -data consistency -more info from same amt of data -sharing of data -improved integrity and security -improved data accessibility -improved backup & recovery services disadvantages: complexity -size (big) -cost (really pricey) -cost of conversion (extra hardware, training staff, etc) -performance (can get slow) -greater impact of failure (failure of certain aspects can bring whole db to a hault)

What is security?

The protection of the database from unauthorized users, which may involve passwords and access restrictions.

What are the differences between DDL (Data Definition Language) and DML (Data Manipulation Language)? What operations can you do in ea. language?

-DDL is a language that allows the DBA or user to describe and name the entities, attributes, and relationships required for the application, together with any associated integrity and security constraints. (create, drop and renames objects in db) -The DML is a language that provides a set of operations to support the basic data manipulation operations on the data help in the database. (select, insert, delete data) The part of a DML that involves data retrieval is called a query language.

What is a logical database designer?

The logical database designer is concerned with identifying the data (that is, the entities and attributes), the relationships between the data, and the constraints on the data that is to be stored in the database.

Give 4 examples of a database system

-a system that contains customer invoice numbers -a hospital with its patient records -a calorie counter database -police containing criminal records

What are the 3 generations of DBMS?

1. CODASYL & hierarchical approaches represented the first gen of DBMS. Based on concept that smaller components come together as parts of larger components and so on, until final product is assembled (think of an upside down tree) 2. Relational DBMS are 2nd gen. (think of tables that have relation to each other, and keys as in a bullet journal) 3. Objected-oriented DBMS (OODBMS) & Object-relational DBMS (ORDBMS) - evolution represents the 3rd gen

Name 4 objected-based data models.

1. Entity-Relationship (ER) 2. Semantic 3. Functional 4. Object-oriented

What are the 2 types of data independence?

1. Logical data independence: is the ability to modify the conceptual scheme without making it necessary to rewrite application programs. Such a modification might be adding a field to a record; an application program's view hides this change from the program. 2. Physical data independence: is the ability to modify the physical scheme without making it necessary to rewrite application programs. Such modifications include changing from unblocked to blocked record storage, or from sequential to random access files.

What is a database application program?

A computer program that interacts with the database by issuing an appropriate request (i.e., SQL statement) to the DBMS

What is a data model? Discuss the main types of data models.

A data model is a collection of concepts that can be used to describe a set of data, the operations to manipulate the data, and a set of integrity constraints for the data. They fall into three broad categories: -object-based data models -record-based data models -physical data models. The first two are used to describe data at the conceptual and external levels; the latter is used to describe data at the internal level.

What is concurrency control and why does a DBMS need a concurrency control facility?

A mechanism to ensure that the database is updated correctly when multiple users are updating the database concurrently. This avoids inconsistencies from arising when 2 or more transactions are executing and at least one is updating the database.

What is a hierarchical data model?

A restricted type of network model. Data is represented as collections of records and relationships are represented by sets. However, hierarchical model allows a node to have only one parent. Can be represented as a tree graph.

What is a database?

A shared collection of logically related data and its description, designed to meet the needs of an organization

What is a database management system?

A software (computer application) that allows you to work with databases on a computer (also allows user to control, define, and maintain database)

What is a transaction, & give an example

A transaction is a series of actions, carried out by a single user or application program which accesses or changes the contents of the database.

Discuss the function and importance of conceptual modeling.

Conceptual modeling is the process of constructing a detailed architecture for a database that is independent of implementation details, such as the target DBMS, application programs, programming languages, or any other physical considerations. The design of the conceptual schema is critical to the overall success of the system. It is worth spending the time and effort necessary to produce the best possible conceptual design.

What is a relational data model?

Data and relationships are represented as tables, each of which has a number of columns with a unique name

What is the concept of data independence & its importance in a database environment?

Data independence is when upper levels are unaffected by lower levels.

What is a network data model?

Data represented as collections of records, and relationships are represented by sets. Compared with the relational model, relationships are explicitly modeled by the sets, which become pointers in the implementation. Records are also organized as generalized graph structures.

The ANSI-SPARC database architecture uses three levels of abstraction: what are they?

External, Conceptual, and Internal.

Describe the approach taken to the handling of data in the early file-based systems. Discuss the disadvantages of this approach.

File-based systems were application first then data, and data would be stored in a file or files from the program. Disadvantages include duplication of data, incompatible file formats, the difficulty (or impossibility) of cross referencing data, restricted to one user at a time, and vast difficulty of recovering data in case of a hardware/software failure

What are the 5 components of the DBMS environment and how do they relate to each other?

Hardware & Software: Machine Data: the bridge Procedures & People: Human

Define the term "database integrity". How does DB integrity differ from DB security?

Integrity refers to the correctness & consistency of stored data and can be considered as another type of DB protection. While integrity is related to security, it has wider implications: integrity is concerned with the quality of the data itself and is usually expressed in terms of /constraints/, which are consistency rules that the DB is not permitted to violate.

What is the difference between procedural DMLs and non-procedural DMLs?

Procedural DML - a language that allows the user to tell the system what data is needed and exactly how to retrieve the data Non-procedural DML - a language that allows the user to state what data is needed rather than how it is to be retrieved

Name 3 record-based data models.

Relational data model, network data model, hierarchical data model

What is a data administrator (DA)?

The DA is a business oriented individual more involved in requirements gathering, analysis, and design than the DBA. They establish the flow of data around the organization and between databases and other systems.

What is a database administrator (DBA)?

The DBA is responsible for: -Installing and configuring the DBMS -Assisting in the implementation of information systems -Monitoring the performance of the database and tuning the DBMS for optimal performance Maintaining documentation including recording all changes to the database and DBMS. -Ensuring data integrity is maintained and appropriate backups are made. >Mainly concerned with the day to day operational aspects of database systems.

Describe the main characteristics of the database approach and contrast it with the file-based approach

The database approach focuses on data first, then application. Structure of data is kept separate from programs that operate on data- held in the system catalog or data dictionary. Programs can now share data and cross reference. Reduction in redundancy.

What is integrity?

The maintenance of the validity and consistency of the database by use of particular constraints that are applied to the data.

What is a physical database designer?

The physical database designer decides how the logical database design is to be physically realized. This involves: -mapping the logical database design into a set of tables and integrity constraints; -selecting specific storage structures and access methods for the data to achieve good performance; -designing any security measures required on the data.

What is data independence?

The separation of underlying file structures from the programs that operate on them.

What is the function and importance of the system catalog?

The system catalog is one of the fundamental components of a DBMS. It contains "data about the data," or metadata. The catalog should be accessible to users. The Information Resource Dictionary System is an ISO standard that defines a set of access methods for a data dictionary. This standard allows dictionaries to be shared and transferred from one system to another.

What is data?

Various objects, entities, facts, etc., that are of use to the user