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29 Cards in this Set
- Front
- Back
A specific data file was created for each application?
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File Oriented Processing
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Create a single data repository to support numerous applications?
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Data Oriented Processing
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Flat file problems with data redundancy? (4)
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1. data storage-lots of it
2. data updating-any changes have to be done multiple times 3. currency of info- may not update all relevant files ea. time 4. Task-Data dependency- user's inability to obtain additional information on his or her needs |
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Advantages of centralized Database?
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1. No data redundancy
2. Single update 3. current values 4. Task-data independence |
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Disadvantages of Centralized Database?
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-can be costly to implement
-can only run in certain operating environments -have to train users |
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Tables in a Relational Database:
Rows are called____? |
Instances or Records
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Tables in a Relational Database:
Columns are called____? |
Fileds
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Columns in a tables represent ___ of an entity? Example
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Attributes- "date"
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TRUE/FALSE
Can a primary key have more than on attribute? |
True- its called a COMPOSITE KEY
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Tables in an actual relational database are linked together via the use of ___&____?
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Primary and Foreign keys
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A primary uniquely identifies an ____?
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Instance
-ex. sales invoice# uniquely identifies a sales transaction |
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Change of the customers address has to be done to every single record containing this customers' information. Otherwise, it would result in data inconsistency.
a. Insert Anomaly b. Update Anomaly C. Delete Anomaly |
B. Update Anomaly
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A customers information cannot be entered unless he/she has purchased goods/services from the company is?
a. Insert Anomaly b. Update Anomaly C. Delete Anomaly |
A. Insert Anomaly
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If we remove a sale then the customers information will be lost also.
a. Insert Anomaly b. Update Anomaly C. Delete Anomaly |
C. Delete Anomaly
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TRUE/FALSE?
A primary key can consist of multiple fields? |
True
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TRUE/FALSE?
A specific value of primary key can identify multiple instances? |
False- once you get down need to identify
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TRUE/FALSE?
A table can have multiple non-key attributes? |
True- contact info, DOB, email, economic parameters)
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TRUE/FALSE?
A table can have multiple foreign keys? |
True-Ex.Sales can be linked to customer and inventory (Could even have ZERO)
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A relational database logical model consists of ___&___?
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Entities and Relationships.
Entities- "sales" and "customers" Relationship- is "made to" |
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____ of a relationship represent Business rules for how many times an instance of entity A has an association with the instances in entity B.
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Cardinalities
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If a relationship has a ( ,N) and ( ,N) relationship you need to?
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-Create another table
-Combine the names of the 2 tables with an underscore -Use the combo of the two related entities as the new primary key -aka COMPOSITE KEY |
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To determine the foreign keys for a table you need to?
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- post the primary key of table B [the one with ( ,N)] to table A ( ,1) as a foreign key
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What is querying?
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We ask questions about data in the database and design queries to manipulate and combine data in different ways
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Two ways to develop queries?
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Structural Query Language- where user enters commands according to pre-defined syntax
AND Query by Example- user starts with a sample of the table(s) columns and marks the fields he wants to include in the answer- downside-have to do step by step-multiple queries |
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In a Query by Example, mathematically combine values from different fields for each row is called?
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Horizontally calculations
(Do before vertically integrate and can't do in the same query) |
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In a Query by Example, summarizing data with a field(column)?
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Vertically aggregating
(in access SUM) |
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Things that the organization acquires and uses and have economic values?
a. Events b. Agents c. Resources |
c. Resources
ex.cashing and inventory |
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Various business activities about which management wants to collect information for planning or control purposes?
a. Events b. Agents c. Resources |
a. Events
ex. sales and purchases |
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People and organizations who participate in events and about whom information is desired for planning, control, and evaluation purposes?
a. Events b. Agents c. Resources |
b. Agents
ex. employees and vendors |