Transcript Document
Denis Gnatyuk
CMC department
AGENDA
Data Access Component
Disconnected Data
The DataSet
DataAdapter
DataView
Typed DataSets
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BUILDING A DATA ACCESS COMPONENT
Layered design with a database class
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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
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DATA PACKAGE
Provides all database fields as public properties
[ C# 3.0 ]
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STORED PROCEDURE
- needs to retrieve, insert, and update information
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DATA UTILITY CLASS
-
performs the actual database operations
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CONCURRENCY STRATEGIES
Last-in-wins updating
Match-all updating
Timestamp-based updating
Changed-value updating
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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
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THE DATASET
10
DATASET XML AND MISCELLANEOUS METHODS
11
DATAADAPTER CLASS
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DATAADAPTER CLASS
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FILLING A DATASET
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MULTIPLE TABLES AND RELATIONSHIPS
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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
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SEARCHING FOR SPECIFIC ROWS
Select() method allows to search rows in DataTable
using a SQL expression
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DATA BINDING
1.
2.
(
)
3.
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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
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FILTER OPERATORS
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CALCULATED COLUMNS
DataColumn.Expression property
DataTable.Columns.Add( … )
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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
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To create a typed DataSet, you need XSD (XML schema document)
WEB APPLICATIONS AND THE DATASET
Straightforward
commands
DataSet
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WEB APPLICATIONS AND THE DATASET
Perform direct
updates using
straightforward
commands
Retrieve data into
the DataSet
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СПАСИБО ЗА ВНИМАНИЕ!
???
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