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Transcript
Chapter
1
Chapter 5
Introduction toDatabase
Accounting Information
Management
Systems
Systems
1
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
3
Attribute hierarchy for entity Client
4
Model representations for entities
and attributes
5
Relationships
6
Constraints on data model
relationships
EMPLOYEE
1
Works
N
WORKS_COMPLETED
a. Cardinality constraints
(1,1)
EMPLOYEE
b. Participation
constraints
(0,N)
Works
WORKS_COMPLETED
7
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.
8
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.
9
CLIENT
Schema - billing & HR database
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_RatePay_Rate
TRAINING_COMPLETED
Employee_No. Date Hours Train_code
RELEASE_TIME
Employee_No. Date Hours Vacation_Sick
10
CLIENT
Referential constraints - relational schema
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_RatePay_Rate
TRAINING_COMPLETED
Employee_No. Date Hours Train_code
RELEASE_TIME
Employee_No. Date Hours Vacation_Sick
11
12
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
13
Constructing DBs using SQL
•
•
•
•
Assign name to relation
Assign names to attributes
Specify data type for attributes
Specify constraints, when appropriate, on the
attributes.
14
Other SQL functions
• Update DB – 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
15
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