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القناة الأساسية
@stepbystep001

ومـما زادني شـرفـاً وتـيــهـاً
وكدت بأخمصي أطأ الـثريا
دخولي تحت قولك يا عبادي
وأن صـيَّرت أحمد لي نـبيـا
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The database designers interview prospective database users to understand and document their data requirements.
Anonymous Quiz
92%
T
8%
F
requirements should not be specified in as detailed and complete a form.
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73%
F
27%
T
In parallel with specifying the data requirements, it is useful to specify theknown functional requirements of the application
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96%
T
4%
F
we create a conceptual schema for the database, using a low-level conceptual data model.
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23%
T
77%
F
............ concepts are used for conceptual schema design
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85%
ER model
15%
Relational model
database design techniques : (Bottom Up approach)
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22%
ER Modeling
78%
Normalization
Concentrating on the database structures and constraints during conceptual database design
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83%
ER Model
17%
Relational Model
ER models are readily translated to relations.ER models, also called an ER schema, are represented by ER diagrams.
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96%
T
4%
F
It is useful in developing a conceptual design for the database & is very simple and easy to design logical view of data.
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21%
Relational Mode
79%
ERD
The ......... model describes data as entities, relationships, and attributes
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82%
ERD
18%
Relational Model
Without ER diagrams you can make a database structure & write production code
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27%
T
73%
F
An ............ is a property of an entity or a relationship type.
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13%
entity type
7%
relationship type
80%
attribute
is a set of meaningful associations among entity types
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13%
attribute
79%
relationship type
8%
entity type
is a group of objects with the same properties, which are identified by the enterprise as having an independent existence
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11%
attribute
7%
relationship type
82%
entity type
property or characteristic of an entity type (often corresponds to a field in a table)
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9%
Entities
85%
Attributes
5%
Relationships
–link between entities (corresponds to primary key-foreign key equivalencies in related tables)
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3%
Entities
5%
Attributes
92%
Relationships
Diamonds: entity sets
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18%
T
82%
F
A definable thing—such as a person, object, concept or event—that can have data stored about it.
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86%
Entities
12%
Attributes
2%
Relationships
Think of entities as .........
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90%
nouns
10%
verbs
can be defined solely by its own attributes.
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90%
Strong entity
10%
Weak entity