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Denis Gnatyuk
CMC department
AGENDA
Data Access Component
? Disconnected Data
? The DataSet
?
?
?
?
DataAdapter
DataView
Typed DataSets
2/25
BUILDING A DATA ACCESS COMPONENT
Layered design with a database class
3/25
BUILDING A DATA ACCESS COMPONENT
Open and close connections quickly
? Implement error handling
? Follow stateless design practices
? Don?t let the client use wide-open queries
?
4/25
DATA PACKAGE
?
Provides all database fields as public properties
[ C# 3.0 ]
5/25
STORED PROCEDURE
- needs to retrieve, insert, and update information
6/25
DATA UTILITY CLASS
-
performs the actual database operations
7/25
CONCURRENCY STRATEGIES
?
Last-in-wins updating
?
Match-all updating
?
Timestamp-based updating
?
Changed-value updating
8/25
DISCONNECTED DATA
DataSet is easier to use than a DataReader, if you:
?
need a convenient package to send the data to another
component
?
need a convenient file format to serialize the data to disk
?
want to navigate among several different tables
?
want to use data binding with user interface controls
?
want to manipulate data as XML
?
want to provide batch updates
9/25
THE DATASET
10
DATASET XML AND MISCELLANEOUS METHODS
11
DATAADAPTER CLASS
12/25
DATAADAPTER CLASS
13/25
FILLING A DATASET
14/25
MULTIPLE TABLES AND RELATIONSHIPS
15/25
REFERENTIAL INTEGRITY
Can?t delete a parent record if there are linked child
rows
? Can?t create a child record that references a
nonexistent parent
?
createConstraints = false
16/25
SEARCHING FOR SPECIFIC ROWS
Select() method allows to search rows in DataTable
using a SQL expression
17/25
DATA BINDING
1.
2.
(
)
3.
18/25
DATAVIEW CLASS
DataView is a representation of the data in a DataTable
Filtering (DataView.RowFilter property)
? Sorting (DataView.Sort property)
?
The default DataView ? DataTable.DefaultView
property
19/25
FILTER OPERATORS
20/25
CALCULATED COLUMNS
DataColumn.Expression property
? DataTable.Columns.Add( ? )
?
21/25
TYPED DATASETS
The information about the schema of the DataSet
is already ?hard-coded? into DataSet
? Access table names and field values using
strongly typed property names
?
22/25
To create a typed DataSet, you need XSD (XML schema document)
WEB APPLICATIONS AND THE DATASET
Straightforward
commands
DataSet
23/25
WEB APPLICATIONS AND THE DATASET
Perform direct
updates using
straightforward
commands
Retrieve data into
the DataSet
24/25
СПАСИБО ЗА ВНИМАНИЕ!
?
???
25/25
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