what’s new in system.data. agenda the common programming model the schema discovery api...

What’s New in System.DataWhat’s New in System.Data

AgendaAgenda

The Common Programming Model The Schema Discovery API Enhancements to the DataSet classSQL Server-specific enhancements

ADO.NET 2.0 goalsADO.NET 2.0 goals

ADO.NET 2.0 evolves without revolutions

People like ADO.NET the way it is :)Just upgrade; your code will work

Changes for performance & scalabilityDataSet and DataTable enhanced

Provider-independent APIIntegration with SQL Server 2005

Common programming model

Common programming model

Factory Class HierarchyFactory Class Hierarchy

IDb* interfaces (e.g. IDbConnection)IDb* interfaces (e.g. IDbConnection)

Db* abstract base classes (e.g. DbConnection)Db* abstract base classes (e.g. DbConnection)

Db*Base implementation classesDb*Base implementation classes

SqlSql OleDbOleDb ODBCODBC OracleOracle 33rdrd Party 1Party 1

33rdrd Party 2Party 2

Provider-Independent apps code to this layer

Provider-specific apps code to this layer

Common Provider ClassesCommon Provider Classes

In System.Data.Common namespace:for example:

DbCommand DbCommandBuilder DbConnection

DataAdapter DbDataAdapter DbDataReader

DbParameter DbParameterCollection DbTransaction

DbProviderFactory DbProviderFactories DbException

Using a Provider FactoryUsing a Provider FactoryImport the Required Namespace:using System.Data.Common

Create the Factory Instance:static DbProviderFactory factory = DbProviderFactories.GetFactory("provider-name")

Create Required Object Instances:DbConnection con = factory.CreateConnection()

DbCommand cmd = con.CreateCommand()

Provider EnumerationProvider EnumerationEach provider has an invariant name

for example: "System.Data.SqlClient", "System.Data.OracleClient"

Get a List of Installed Provider FactoriesDataTable dt = DbProviderFactories.GetFactoryClasses()

DbProviderFactory factory = DbProviderFactories.GetFactory(dt.Rows[x])

... or ...DbProviderFactory factory = DbProviderFactories.GetFactory( dt.Select("InvariantName='System.Data.SqlClient'") [0]["InvariantName"].ToString());

When Should I Use It?When Should I Use It?An OPTION only

Designed for tool and IDE suppliersConnection string details depends on database typeParameter names depend on provider type

PerformanceNo layer of overheadCreate factory once and reuseOtherwise equal Performance

the base class is returned from factory object

Schema Discovery APISchema Discovery API

Schema Discovery APISchema Discovery API

Get a List of Schemas:DataTable dt = conn.GetSchema("MetaDataCollections")

Get a Specific Schema:DataTable dt = conn.GetSchema("collection-name")

Get Selected Details from a Schema:DataTable dt = conn.GetSchema("collection-name",

restriction-array)

Schema SelectionSchema Selection

CollectionName Restrictions

CollectionName Restrictions

MetaDataCollections n/a Views 3

DataSourceInformation

n/a ViewColumns 4

DataTypes n/a Parameters 4

Restrictions n/a Procedures 4

ReservedWords n/a ProcedureColumns 4

Users 1 ForeignKeys 4

Databases 1 IndexColumns 5

Tables 4 Indexes 4

Columns 4 UserDefinedTypes 1

GetSchema("GetSchema("collection-namecollection-name",", restrictions[restrictions[xx])])

Some Metadata CollectionsSome Metadata Collections

Columns schema metadata collection

table_catalog table_schema table_name

column_name ordinal_position column_default

is_nullable data_type character_maximum_length

character_octet_length

numeric_precision numeric_precision_radix

numeric_scale datetime_precision character_set_catalog

character_set_schema character_set_name collation_catalog

Tables schema metadata collection

table_catalog table_schema table_name table_type

= restriction that can be used for selecting items

DataSet enhancementsDataSet enhancements

DataSet Serialization in .NET 1.1

DataSets serialize through DiffGram scripts

DataSetISerializable

Formatter

XML

SoapFormatter:BinaryFormatter:CompactFormatter

http://www.freewebs.com/compactFormatter/downloads.html

DataSet Serialization in .NET 2.0DataSet Serialization in .NET 2.0Binary Serialization of Contents

V 1.x DataSet always serialized to XMLgood for data interchange, bad for performance

Binary serialization an option in V 2.0fast and compact, especially as row counts increasejust set: DataSet.RemotingFormat = SerializationFormat.Binary

Internal Indexing of RowsInserts and deletes are log-nUpdates almost constant

Binary vs XML SerializationBinary vs XML Serialization

100 1000 10000 100000

Row s in DataSet

En

d-t

o-E

nd

Tim

e (l

ow

er is

bet

ter)

Xm l

Binary

Up to 80 x faster for large DataSets!Up to 80 x faster for large DataSets!

Loading a DataSetLoading a DataSetDataAdapter enhancements

DataAdapter.FillLoadOption and AcceptChangesDuringUpdate properties

DataSet.Load methodLoad(DataReader [, load-option] [, tables-array])optionally can use FillErrorEventHandler event to trap errors

The LoadOption EnumerationThe LoadOption Enumeration

Used by Load and Merge methodswhat happens when loading a row with same key

ds.Merge(loadoption, preservechanges)use preservechanges=True for overwriting original values but not current values

the LoadOption enumeration helps to support other scenarios

e.g. merging data from a different DB or from file

The LoadOption enumerationThe LoadOption enumeration

PreserveCurrentValues (default)overwrites original values, keeps current valuesgood to resync with original DB after a conflict

UpdateCurrentValuesoverwrites current values, keeps original onesgood to read data from DB without losing original data loaded in the dataset

OverwriteRowoverwrites both values, sets the row as unchanged

The LoadOption EnumerationThe LoadOption EnumerationRowState of

Existing RowPreserveCurrentValues (the default value)

UpdateCurrentValues OverwriteRow

Added Current = ExistingOriginal = IncomingRowState = Modified

Current = IncomingOriginal = ExistingRowState = Added

Current = IncomingOriginal = IncomingRowState = Unchanged

Modified Current = ExistingOriginal = IncomingRowState = Modified

Current = IncomingOriginal = ExistingRowState = Modified


Deleted Current = ExistingOriginal = IncomingRowState = Deleted

* Undo Delete Current = IncomingOriginal = ExistingRowState = Modified

* Undo Delete Current = IncomingOriginal = IncomingRowState = Unchanged

Unchanged Current = IncomingOriginal = IncomingRowState = Unchanged

Current = IncomingOriginal = Existing* if new value = existing value: RowState = Unchanged * else: RowState = Modified


No matching existing row in the table


Current = IncomingOriginal = ExistingRowState = Added


Stand-alone DataTable InstancesStand-alone DataTable InstancesCommon DataSet operations now also available on DataTable:

ReadXml, ReadXmlSchema, WriteXml, WriteXmlSchema, Clear, Clone, Copy, Merge

DataTable is now auto-serializable:

return a DataTable instance from a Web Service or via Remoting

Loading and Using a DataTableLoading and Using a DataTable

DataAdapter.Fill(DataTable)DataAdapter.Fill(DataTable[ ])

and more, including subsets of rows

DataAdapter.Update(DataTable)DataTable.Load(DataReader [, load-option] [, FillErrorEventHandler])

new methods: BeginLoadData, Load, EndLoadData

DataTable.GetDataReader methodstream data from a DataTable

1000 10000 100000 200000

Loaded Row s

Tim

e v1.x

v2.0

DataSet Load PerformanceDataSet Load Performance

3 times as fast for 100,000 rows - and even better with more!3 times as fast for 100,000 rows - and even better with more!

Using LoadDataRow APIUsing LoadDataRow API

More New FeaturesMore New FeaturesRowState values are now updateable

New methods: DataRow.SetAdded and DataRow.SetModifieduse Delete and AcceptChanges/RejectChanges for other states

DataTable.GetDataReader methodreturns a DataTableReaderyou can specify which tables to include

DataView.ToTable methodfiltering and sorting, can include only a subset of columnsdt = dv.ToTable(tableName, boolDistinct, columnNames())

Batched UpdatesBatched UpdatesDataSet updates are normally processed one by oneBatching reduces network round-trips

DataAdapter.UpdateBatchSize = batch_sizeWorks inside transactionsWorks with SQL Server 7.0, 2000, 2005

Also available for OracleClient classesMinor limitations

max 2000 parametersmaxrows = 2000 / paramsper rowoptimal numrows = 100-500 rows

XML Data Types in a DataSetXML Data Types in a DataSetThe DataTable accepts columns of

data-type 'xml'type is System.Data.SqlTypes.SqlXml

in Beta 2 defaults to a String unless DataAdapter.UseProviderSpecificType = true

exposed as an XPathDocument instancecan also be accessed via an XmlReadermakes it easier to work with XML as a document rather than a rowset of valuesmaintains fidelity of the XML content

User-Defined Types in a DataSetUser-Defined Types in a DataSetPopulate DataSet with SQL or Stored ProcedureUpdate with SQL Statement or Stored Procedure

create the Command and Parametersparam = da.UpdateCommand.Parameters.Add ("@name",SqlDbType.Udt)

param.UdtTypeName = "type-name"

param.SourceColumn = "column-name"

or can use a SqlCommandBuilderuse timestamp column for conflict resolutionotherwise UDT conflicts will not be detected

SqlClient enhancementsSqlClient enhancements

Asynchronous CommandsAsynchronous CommandsIdeal for multiple database queriesUsual Beginxxx and Endxxx modelSupports Polling, Wait and Callback modelsCatching asynchronous execution errorsShould not generally be used with MARS

use a separate connection for each Command

Add "async=true" to connection stringDoesn’t work on Win9x and ME clients

~ 3 secs

Application

Synchronous LatencySynchronous Latency

Rowset 1

Rowset 2

Rowset 3

Connection

Total time until all three displays filled:

Database2Latency 8 secs


Connection

Connection

~ 11 secs ~ 16 secs

Data 1

Data 1

Data 1Data 1Data 1

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Application

Asynchronous ExecutionAsynchronous Execution

Rowset 1

Rowset 2

Rowset 3

Connection1

Connection2

Connection3

~ 8 secs Total time until all three displays filled:

Data 1

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Asynchronous Polling ModelAsynchronous Polling ModelStart asynchronous command execution:IAsyncResult result = MyCommand.BeginExecuteReader()

Wait until execution is complete:while (! result.IsCompleted) {

// execute other code here

}

Fetch results:SqlDataReader reader = MyCommand.EndExecuteReader(result )

Asynchronous Wait (All) ModelAsynchronous Wait (All) ModelStart one or more asynchronous

commands:IAsyncResult resultx = MyCommand.BeginExecuteReader()

Wait for all commands to complete:WaitHandle.WaitAll(new WaitHandle[] {result1.AsyncWaitHandle, result2.AsyncWaitHandle, result3.AsyncWaitHandle}, timeout-ms, true)

Fetch results:SqlDataReader reader = MyCommand.EndExecuteReader(resultx)

Ideal for ASP.NET Web applications

Asynchronous Wait (Any) ModelAsynchronous Wait (Any) ModelStart one or more asynchronous commands as an array of IAsyncResult instances:IAsyncResult resultx = MyCommand.BeginExecuteReader()

Wait for each command to complete:for(int i=0; i < result_array.Length, i++) {

index = WaitHandle.WaitAny(result_array,

timeout, true);

switch(index) {

case 0: SqlDataReader reader =

MyCommand.EndExecuteReader(resultx);

...etc...

Asynchronous Callback ModelAsynchronous Callback ModelStart execution, specifying callback

and passing command as the AsyncState:MyCommand.BeginExecuteReader(new AsyncCallback(MyCallback), cmd)

Provide a callback handler:void MyCallback(IAsyncResult result) {

SqlCommand cmd =

(SqlCommand) result.AsyncState;

SqlDataReader reader =

cmd.EndExecuteReader(result);

}

Catching Timeouts and ErrorsCatching Timeouts and Errors

For the WaitOne and WaitAll methods:use try/catch around each "End" method

For the WaitAny method:return value is equal to timeout value

When using the Callback model:use try/catch around "End" method

More SqlClient enhancementsMore SqlClient enhancements

Connection-level statisticsStatisticsEnabled propertyRetrieveStatistics method (return IDictionary)ResetStatistics method

AttachDbFileName in connection stringmust be absolute path in ADO.NET 1.xcan be a relative path in ADO.NET 2.0great to support SQL Server 2005 Express (MSDE)

Enhancements for SQL Server 2005Enhancements for SQL Server 2005

Multiple Active ResultSets (MARS)Multiple Active ResultSets (MARS)

Opening a second “cursorless” resultset on the same connection

ADO opens a new connection behind the scenesADO.NET 1.x throws an exception

Fully supported in ADO.NET 2.0 & SQL Server 2005

required changes in network librariescommands on same connection share the same transaction

SqlDependency classSqlDependency classADO.NET 2.0 SqlDependency class tracks dependencies on query resultsBuilt on SQL Server 2005 Query Notifications

or Notifications Service for SQL 2000Query Notifications add-in available

Wraps the low-level SqlNotificationRequest type

Doesn’t require an open connection

Don’t use with many clientsall would refresh data at the same time

SqlCommand cmd;cmd = new SqlCommand("SELECT * FROM Authors", conn);SqlDependency dep = new SqlDependency(cmd);dep.OnChanged += new OnChangedEventHandler(OnDepChanged);cmd.ExecuteReader();

ASP.NET Cache DependencyASP.NET Cache Dependency

SqlCacheDependency is ASP.NET-specific wrapper that work with SQL Server 7.0 and 2000 too

invalidates data in the Cache based on table (not query!) changes

Enable notifications for required tablesCreate triggers to handle incoming statementsCommand-line tool (aspnet_regsql) or methods of SqlCacheDependencyAdmin

// SELECT … WHERE country=‘USA’ trigger also for ‘UK’SqlCacheDependency dep;dep = new SqlCacheDependency(database, table);Cache.Insert("MyData", dataSet, dep);

Notifications & SqlDependencyNotifications & SqlDependencyCache the data and then be notified

when ANYTHING happens that would give a different result if the query was re-executedUses SQL Server 2005 Query Notifications

bind SqlDependency to Command and execute itfully integrated with ASP.NET as well

Notifications Service for SQL 2000Query Notifications add-in available

Support for new data typesSupport for new data types

ADO.NET 2.0 supports SQL Server 2005 XML native data type, user-defined types

SqlXml and SqlUdt in System.Data.SqlTypes

also supported by SqlParameter

DataReader returns UDTs and XML dataGetValue and GetString, respectively

the new SqlMetaData type can return extended properties

XML schema collection for XML typedatabase name of a UDT

The XML Data TypeThe XML Data Type

SQL Server 2005 provides an XML database and schema repository

XML data-typing and indexing are supported for XML columns

XML data type can be used in T-SQLwhen inserting and selecting data

when querying and updating data

Using the XML Data TypeUsing the XML Data Type

Accessing XML data from ADO.NETreading XML with a DataReader

updating XML with a SQL statement

XML Data Manipulation LanguageXML DML allows updates to the data within XML columns using T-SQL

functions include: modify(), insert(), delete(), replace(), column() and value()

XML DML QueriesXML DML QueriesMethods of the "xml" data type within SQL ServerQuery the data in an XML column to get individual values without retrieving all of itManipulate the data in an XML column without retrieving any of itExample:UPDATE table SET xml-column.modify('

replace value of (/root/element)[index]

with "new-value"')

WHERE column-name = criteria

Password changingPassword changing

SQL Server 2005 supports password expiration

requires Windows Server 2003

the ChangePassword method of the SqlConnection type

you shouldn’t hard-code the password in the connection string (a sound practice anyway)store in config file in encrypted format

What else?What else?

Promotable TransactionsPromotable TransactionsAutomatic promotion of local transactions into distributed ones

Uses TransactionContext

Fully integrated with the classes in System.Transactions namespace

Works with transactions started in SQL Server 2005 CLR code

Context flows even if you start in-proc

Don't promote single RM transactions

Auto-promoting a TransactionAuto-promoting a TransactionInitialize the transaction scope:TransactionScope scope = new TransactionScope (TransactionScopeOptions.RequiresNew);

Create a connection and do workDo *not* enrol - uses a local transaction

Create second connection and do worktransaction auto-promoted to distributed

Vote to commit or rollback:scope.Consistent = [true|false];

Dispose of transaction when complete:scope.Dispose();

TracingTracing

OLEDB lacks a standard trace modemakes it harder to solve OLEDB and ADO problems

ADO.NET 2.0 traces every API callsimilar to ODBC tracingall Microsoft providers are instrumentedopen standard for 3rd party provider writers

DataSet has built-in diagnostics too

Support for untrusted appsSupport for untrusted apps

in ADO.NET 1.1 only the SQL Server provider can be used in partially-trusted appsin ADO.NET 2.0 all four Microsoft providers are supported in this scenario

necessary for ClickOnce deployment

Must be enabled from .NET configuration panel

Other ADO.NET 2.0 enhancementsOther ADO.NET 2.0 enhancements

Doesn’t depend on MDACBetter error handling and clearer error messagesBetter control on connection pooling (SqlClient and OracleClient)

SqlConnection.ClearPool clears a specific poolSqlConnection.ClearPools clears all the pools in an appdomain

Even more for SQL Server 2005Even more for SQL Server 2005

Support for snapshot isolation levelTransparent support for client failover

when the a SQL Server instance fails and work is shifted to the backup (“witness”) instance

SummarySummaryUnderstood how to use the Common Programming Model to write provider-independent codeExplored the use of the Schema Discovery API to examine the schema and structure of databasesReviewed the enhancements to the DataSet class that provide better performance and increased usability

Microsoft®Microsoft®

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