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CHAPTER 12 Databases for Online Analytical Processing
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Demystified / Databases Demystified / Oppel/ 225364 -9 / Chapter 12
Data Marts
A data mart is a subset of a data warehouse ... contains more data than a data warehouse.
e. The project has a lower overall cost than a data warehouse project.
16. Building a data warehouse first, foll...
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... complicated joins and
calculations from the database users. For example, views can easily
calculate ages based on birth dates, and they can summarize data in
nearly any way imaginable.
220
Databases ... numeric digits and
cannot be larger than 99 ,99 9 (five digits) or smaller than 99 ,99 9 (again, five digits).
Also, because the scale is 0, it cannot have decimal digits (that is, it must...
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... 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 interrelated data items that are managed as a ... database can be defined as the file
that contains the data items. Oracle Corporation defines their database as a collec
-
tion of physical files that are managed by an instance of...
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... screen
Constraints
A constraint is a rule placed on a database object (typically a table or column) that
restricts the allowable data values for that database object in some way. These are
most important ... relational databases were built by both IBM and UC Berkeley.
e. Nearly all the commercial relational databases are descendents of either
System R or INGRES.
18. Currently avai...
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... unmatched data to NULL, and
because null values are not greater than 1/1/ 199 8 (and in fact are not greater
than, less than, or equal to anything), the criteria as written in Example 3 -9
would eliminate ... 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...
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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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... systems. Databases that store historical
data used solely for analytical purposes are not as subject to insert, update, and de
-
lete anomalies. Chapter 12 contains more information on databases that ... 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...
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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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•
Flows of data are shown using l...
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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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... Control Language (DCL), 90 , 122–124
Data Definition Language (DDL), 90 , 118–122
data encryption, 256–257
data flow diagram, 194 – 196
data integrity, 214
Data Manipulation Language (DML), 90 ,
114–118
tuning ... Autonomous
e. Analog
82. Database locks:
a. Are implemented in exactly the same way by all major database vendors
b. Are controls placed by the DBMS to reserve data so updates...
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