Chapter 1 In-lab Quiz Next week Database Systems: Design, Implementation, & Management, 7th Edition, Rob & Coronel

Structural and Data Dependence Structural dependence Access to a file depends on its structure Data dependence Changes in the data storage characteristics without affecting the application program’s ability to access the data Logical data format How the human being views the data Physical data format How the computer “sees” the data Database Systems: Design, Implementation, & Management, 7th Edition, Rob & Coronel

Field Definitions and Naming Conventions Flexible record definition anticipates reporting requirements by breaking up fields into their component parts Database Systems: Design, Implementation, & Management, 7th Edition, Rob & Coronel

Field Definitions and Naming Conventions (continued) Database Systems: Design, Implementation, & Management, 7th Edition, Rob & Coronel

Data Redundancy Data redundancy results in data inconsistency Different and conflicting versions of the same data appear in different places Errors more likely to occur when complex entries are made in several different files and/or recur frequently in one or more files Data anomalies develop when required changes in redundant data are not made successfully Database Systems: Design, Implementation, & Management, 7th Edition, Rob & Coronel

Data Anomalies Types of data anomalies: Update anomalies Occur when changes must be made to existing records Insertion anomalies Occur when entering new records Deletion anomalies Occur when deleting records Database Systems: Design, Implementation, & Management, 7th Edition, Rob & Coronel

The Database System Environment Database system is composed of five main parts: Hardware Software Operating system software DBMS software Application programs and utility software People Procedures Data ASK FOR PARTICIPATION Database Systems: Design, Implementation, & Management, 7th Edition, Rob & Coronel

The Database System Environment (continued) Database Systems: Design, Implementation, & Management, 7th Edition, Rob & Coronel

DBMS Functions Manage DB structure and controls access Share data among multiple users Make data management more efficient and effective Integrated view of organization’s operations Promotes data consistency and integrity Quick answers to ad hoc queries Security Last time – DBMS functions: INTEGRITY – data must be Accurate, relevant, and timely Database Systems: Design, Implementation, & Management, 7th Edition, Rob & Coronel

DBMS Functions DBMS performs functions that guarantee integrity and consistency of data Data dictionary management defines data elements and their relationships Data storage management stores data and related data entry forms, report definitions, etc. Data dictionary – filed names, definitions, relationships, i.e. Phone number in customer file and in order file Data storage management with Oracle: form and report creation Database Systems: Design, Implementation, & Management, 7th Edition, Rob & Coronel

DBMS Functions (continued) Data transformation and presentation translates logical requests into commands to physically locate and retrieve the requested data Security management enforces user security and data privacy within database Database Systems: Design, Implementation, & Management, 7th Edition, Rob & Coronel

DBMS Functions (continued) Multiuser access control uses sophisticated algorithms to ensure multiple users can access the database concurrently without compromising the integrity of the database Backup and recovery management provides backup and data recovery procedures Data integrity management promotes and enforces integrity rules INTEGRITY – relationships created, validity checks (numeric, char, length, postal code), domain checks, Database Systems: Design, Implementation, & Management, 7th Edition, Rob & Coronel

DBMS Functions (continued) Database access languages and application programming interfaces provide data access through a query language Database communication interfaces allow database to accept end-user requests via multiple, different network environments Access language: SQL, structured, not procedural, user defines what to do not how to do it Database Systems: Design, Implementation, & Management, 7th Edition, Rob & Coronel

How many records does the file contain? How many fields are there per record? What problem would you encounter if you wanted to produce a listing by city? How would you solve this problem by altering the file structure? If you wanted to produce a listing of the file contents by last name, area code, city, state, or zip code, how would you alter the file structure? What data redundancies do you detect, and how could these redundancies lead to anomalies? 5. B. Parker occurs three times, changes must be made three times…project managed by one manager but manager can manager several projects (1:M) If B Parker does not manager one project what happens??? Database Systems: Design, Implementation, & Management, 7th Edition, Rob & Coronel

Identify and discuss the serious data redundancy problems. Looking at the EMP_NAME and EMP_PHONE contents, what change(s) would you recommend? Identify the different data sources. What new files should you create to help eliminate the data redundancies? Charge for job code EE changes from 85 to 95$. employee June H. Sattlemeier is deleted from the file, you also lose information about the existence of her JOB_CODE = EE, its hourly charge of $85.00, and the PROJ_HOURS = 17.5. The loss of the PROJ_HOURS value will ultimately mean that the Coast project costs are not being charged properly, thus causing a loss of PROJ_HOURS*JOB_CHG_HOUR = 17.5 x $85.00 = $1,487.50 to the company. Fields come from different things (entities) – project, employee, job Database Systems: Design, Implementation, & Management, 7th Edition, Rob & Coronel