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Databases Demystified a self teaching guide phần 3 potx
... row are called aggregate functions. The following table shows
aggregate functions that are commonly used in relational databases:
Function Name Description
AVG Calculates the average value for a ... printer profile
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beauty of relational databases is that we need...
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... Quizzes and Final Exam 32 5
Chapter 1 32 5
Chapter 2 32 5
Chapter 3 326
Chapter 4 32 6
Chapter 5 32 6
Chapter 6 32 6
Chapter 7 32 6
Chapter 8 32 7
Chapter 9 32 7
Chapter 10 32 7
Chapter 11 32 7
Chapter 12 32 7
Index ... models, a brief his
-
tory of databases, and the rationale for focusing on the relational model.
Properties of a Database
A database is a collection of...
Databases Demystified a self teaching guide phần 2 pot
... Deleting database objects
c. Adding new database objects
d. Adding data items to existing database objects
e. Deleting data items from existing database objects
CHAPTER 1 Database Fundamentals
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Monday, ... screen
Constraints
A constraint is a rule placed on a database object (typically a table or column) that
restricts the allowable data values fo...
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... that ends every SQL statement.
In Oracle, a transaction is automatically started for each database user session as soon
as the user connects to the database. At any time, the database user can ... table’s data.
The ALTER TABLE Statement
The ALTER TABLE statement may be used to change many aspects of the definition
of a database table. Again, there is a wide variation in implementation a...
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... normalization rules
•
Storing redundant data in tables
•
Storing summarized data in tables
Note also that normalization is intended to remove anomalies from databases that
are used for online transaction-processing ... identify any additional indexes that
may be necessary to achieve acceptable database performance. An essential out
-
come of this phase is the DDL for creation of the develop...
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... profile
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The Data Flow Diagram
The data flow diagram (DFD) is the most data centric of all the ... profile
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11. The basic components of a flo...
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... considered
a best practice because it can lead to a lack of data sharing. Moreover, placing
geographic or organizational unit names in table names plays havoc every
time the organization changes.
CHAPTER ... synchronizing data updates for
any redundantly stored data
•
More expensive than the centralized model
•
Lack of guidelines and best practices for how to partition data and
applicatio...
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... even to a different version of the same vendor’s database).
Connecting Databases to Java Applications
Java started as a proprietary programming language (originally named Oak) that was
developed ... that
binds the API to the particular database and platform, and a definition known as the
ODBC data source contains the information necessary for a particular application to
connect with...
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... screen
CHAPTER 12 Databases for Online Analytical Processing
30 1
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Data Marts
A data mart is a subset of a data warehouse that supports ... Default screen
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Here are some reasons for creating a data mart:
•...
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... 90,
114–118
tuning DML statements, 286
data marts, 30 1 30 2
data mining, 30 2 30 3
data modelers, 25
Data Query Language (DQL), 90
SELECT statements, 100–114
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Tuesday, ... 147
delete anomaly, 148
insert anomaly, 148
in second normal form, 157–158
update anomaly, 148
ANSI/SPARC, 3
answers
to final exam, 32 8
to quizzes, 3...