Download Database Review

Database Review
Terminology
Concepts
SQL syntax
Analysis Terms
Term/Concept
Definition or Example
Relational Model
?
Relation Instance
?
Relation Schema
?
Database Schema ?
Type Constraint
?
Data Atomiciy
?
Analysis Terms
Term/Concept
Definition or Example
Relational Model
Uses a n-ary relation between attribute sets to
model entity set.
Relation Instance
A table with a column for each attribute which is
atomic; each row represents an entity.
Relation Schema
A relation schema is a relation name (e.g. student,
customer, etc.) followed by a parenthesized list of
attribute names with associated domains, followed
by constraints.
Database Schema Collection of relation schemas.
Type Constraint
Value in column must be of corresponding data
type
Data Atomiciy
Single value in each column
Analysis Terms
Term/Concept
Definition or Example
Key
?
Key Constraint
?
Foreign Key
?
Foreign Key
Constraint
?
Candidate Key
?
Superkey
?
Functional
Dependency
?
Determinant
?
Analysis Terms
Term/Concept
Definition or Example
Key
A set of attributes which uniquely identifies an
entity (row) of a relation (table)
Key Constraint
Any relation or table has at most one row for some
combination of values of key attributes
Foreign Key
An attribute of a relation which serves as a primary
key of another relation
Foreign Key
Constraint
There is a tuple or row of the primary key table with
same value as value of foreign key (referential
integrity
Candidate Key
A minimal set of attributes which is a key
Superkey
Any key including set of all attributes of relation
Functional
Dependency
A set of attributes X which uniquely determines a
set Y of attributes : X  Y
Determinant
Left side of a functional dependency.
Analysis Terms
Term/Concept
Definition or Example
Anomaly
?
Attribute
?
Binary relation
?
Cardinality
Constraint
?
Composite Key
?
Relational
database
?
Analysis Terms
Term/Concept
Definition or Example
Anomaly
An error or inconsistency due to redundant data
resulting from insertion, update or deletion
Attribute
A property possessed by every entity in set
Binary relation
A relation between two entity sets.
Cardinality
Constraint
A bound on the number of times an instance of an
entity can be related to an instance of another
entity
Composite Key
A key consisting of more than one attribute.
Relational
database
A database consisting of relations (tables).
Analysis Terms
Term/Concept
Definition or Example
1st Normal Form
?
Partial
Dependency
?
2nd Normal Form
?
Transitive
Dependency
?
3rd Normal Form
?
Boyce Codd
Normal Form
?
Analysis Terms
Term/Concept
Definition or Example
1st Normal Form
Every attribute is atomic.
Partial
Dependency
A functional dependency in which non-key
attributes are functionally dependent on part but
not all of the primary key attributes.
2nd Normal Form
No partial dependencies
Transitive
Dependency
A functional dependency between two non-key
attributes or attribute sets.
3rd Normal Form
No transitive dependencies,
Boyce Codd
Normal Form
A relation in which every determinant is a
candidate key.
SQL Syntax
• Create Table
• Insert
• Select
• Update
Basic SQL Syntax
• Create Table
Create <Table> ( <List of Attribute-DataType pairs> <List of Constraints>)
• Insert
Insert Into <Table> (<Attributes List>) Values(<Value List>)
• Select
Select <Attributes List> From <Table Expression> Where <Condition>
• Update
Update <Table> Set <Attribute = New_Value List> Where <Condition>
SQL Statements
SQL
Syntax
Create
Create <Table> ( <List of Attribute-DataType pairs> <List of Constraints>)
Example
Create Table Category( Name Text, ID Number, Primary Key(ID))
Insert
Insert Into <Table> (<Attributes List>) Values(<Value List>)
Example
Insert Into Category (Name,ID) Values("Kitchen",1)
Select
Select <Attributes List> From <Table Expression> Where <Condition>
Example
Select Name From Category
Update
Update <Table> Set <Attribute = New_Value List> Where <Condition>
Example
UPDATE Furniture SET Furniture.Price = 20
WHERE Furniture.ID=2
Create
Insert
Select
Update
SQL
Term/Concept
Definition or Example
Create Table
Create <Table> ( <List of Attribute-DataType pairs> <List of
Constraints>)
Example
Statement to create a transaction table as shown below.
SQL
Term/Concept
Definition or Example
Create Table
Create <Table> ( <List of Attribute-DataType pairs> <List of
Constraints>)
Example
Create Table Transaction(XDate date,
Amount Currency,Payee Number,Comment text,
ID number, Primary Key( ID))
Table
SQL
Term/Concept
Definition or Example
Select
Select <Attribute-List> From
<Table-Expression> Where <Condition>
<Attribute-List>
* refers to all attributes or columns
<Table-Expression>
RentalProperty is table
<Condition>
Example
Embedded SQL
in as value of string
variable in front end
ID = PropertyID
Statement to select a rental property where ID is given
ID.
SQL
Term/Concept
Definition or Example
Select
Select <Attribute-List> From
<Table-Expression> Where <Condition>
<Attribute-List>
* refers to all attributes or columns
<Table-Expression>
RentalProperty is table
<Condition>
Example
Embedded SQL
in as value of string
variable in front end
ID = PropertyID
Dim ds As DataSet
sql = "Select * from RentalProperty Where ID=" & Id
ds = ExecuteSql(sql)
SQL – Insert
Term/Concept
Definition or Example
Insert
Insert Into <Table Name> ( <List of Attributes>)
Values ( <List of Values> )
Example
Write statement to insert a transaction
with the values shown below.
Table
SQL – Insert
Term/Concept
Definition or Example
Insert
Insert Into <Table Name> ( <List of Attributes>)
Values ( <List of Values> )
Example
INSERT INTO [Transaction] Values
(#3/1/2009#,100,1,'',1)
Table
SQL – Update
Term/Concept
Definition or Example
Update
Update <Table Name> Set <List of Attribute = Value pairs>
Example
Write an Update statement to change the amount ot the
given transaction to 150.
Table
SQL – Update
Term/Concept
Definition or Example
Update
Update <Table Name> Set <List of Attribute = Value pairs>
Example
UPDATE [Transaction] SET [Transaction].Amount = 150;
Table
SQL – Update
Term/Concept
Select
Example
Definition or Example
SQL – Select
Select
Example
Write a Select Query which select recipes from the joins of
•Category
•Recipe
•RecipeCategories
–
WHERE RecipeCategories.CategoryID = " & catID
SQL – Select
Select
Example
Public Function FindRecipesByCategory(ByVal catID As Integer) As List(Of Recipe)
Dim sql As String
Dim ds As DataSet, dr As DataRow
sql = "SELECT Recipe.*" & _
" FROM Category INNER JOIN (Recipe INNER JOIN RecipeCategories
ON Recipe.ID = RecipeCategories.RecipeID) ON Category.ID =
RecipeCategories.CategoryID " & _
" WHERE RecipeCategories.CategoryID = " & catID
ds = ExecuteSql(sql)
Dim recipes As New List(Of Recipe)
For Each dr In ds.Tables(0).Rows
Dim c As New Recipe(dr)
recipes.Add(c)
Next
Return recipes
End Function
SQL – Select
Public Function FindIngredientsForRecipe(ByVal rid As Integer) As List(Of Ingredient)
Dim sql As String
Dim ds As DataSet, dr As DataRow
sql = "Select ingredient.* from " & _
" (Recipe INNER JOIN RecipeIngredients ON Recipe.ID =
RecipeIngredients.RecipeID) INNER JOIN Ingredient ON
RecipeIngredients.IngredientID = Ingredient.ID " & _
" WHERE Recipe.ID = " & rid
ds = ExecuteSql(sql)
Dim ingredients As New List(Of Ingredient)
For Each dr In ds.Tables(0).Rows
Dim c As New Ingredient(dr)
ingredients.Add(c)
Next
Return ingredients
End Function