Introduction to Accounting Information Systems Chapter 1 Chapter 5 Database Management Systems Introduction to Accounting Information Systems

Learning Objectives Understand techniques to model complex accounting phenomena in E-R diagram Develop E-R diagrams that model effective accounting database structures Recognize components of relational tables and keys to effective DB design Understand use of SQL to create relational tables during implementation Manipulate tables to extract data

Entities/Attributes Entity - object, event, or agent about which data are collected Objects - Inventory, equipment, cash Events - Orders, sales, purchases Agents - Customers, employees, vendors Attribute - item of data that characterizes and entity or relationship

Attribute hierarchy for entity Client

Model representations for entities and attributes

Relationships

Constraints on data model relationships EMPLOYEE WORKS_COMPLETED 1 Works N a. Cardinality constraints EMPLOYEE (1,1) WORKS_COMPLETED Works (0,N) b. Participation constraints

Relational Databases Relation - collection of data representing multiple occurrences of an object, event, or agent. Tuples (rows) - set of data that describe an instance of the entity represented by a relation; like a record in traditional file structure. Attributes (columns) - items of data that characterize an object, event, or agent; like fields in traditional file structure.

Mapping E-R Diagram to Database Create separate relational table for each entity. Determine primary key for each relation. Must uniquely identify any row within table. Determine attributes for each entity. Implement relationships among entities. (Primary key in one table exists as attribute in every table (entity) where relationship specified in E-R. Determine attributes, if any, for relationship tables.

Schema - billing & HR database CLIENT Client_No. Name Street_address City State Zip_code Contact Phone_no WORK_COMPLETED Employee_No. Date Client_No. Hours EMPLOYEE Employee_No. Soc_Sec_No Name Supervisor_No Billing_Rate Pay_Rate TRAINING_COMPLETED Employee_No. Date Hours Train_code RELEASE_TIME Employee_No. Date Hours Vacation_Sick

Referential constraints - relational schema CLIENT Client_No. Name Street_address City State Zip_code Contact Phone_no WORK_COMPLETED Employee_No. Date Client_No. Hours EMPLOYEE Employee_No. Soc_Sec_No Name Supervisor_No Billing_Rate Pay_Rate TRAINING_COMPLETED Employee_No. Date Hours Train_code RELEASE_TIME Employee_No. Date Hours Vacation_Sick

SQL : Relational DB Query Language Used to define database systems query DB for information generate reports from DB access DB from within programs De facto standard DB language

Constructing DBs using SQL Assign name to relation Assign names to attributes Specify data type for attributes Specify constraints, when appropriate, on the attributes.

Other SQL functions Update DB - Query DB using SELECT/WHERE add tuple using INSERT remove tuple using DELETE change attribute value using UPDATE Query DB using SELECT/WHERE Generate standard reports from DB ad hoc (as necessary) repetitive - might generate subschema view

Learning Objectives Understand techniques to model complex accounting phenomena in E-R diagram Develop E-R diagrams that model effective accounting database structures Recognize components of relational tables and keys to effective DB design Understand use of SQL to create relational tables during implementation Manipulate tables to extract data