A.2 The OLE DB Provider
The OLE DB provider interface provides
access to a database through an OLE DB provider installed on your
computer. Most OLE DB providers are supported, but those that use OLE
DB Version 2.5 interfaces aren't supported. Some
unsupported OLE DB interfaces include:
OLE DB provider for ODBC (MSDASQL) OLE DB provider for Exchange (ExOLEDB) OLE DB for Internet Publishing (MSDAIPP)
Table A-3 lists some commonly used OLE DB drivers.
Table A-3. Commonly used OLE DB drivers
|
SQLOLEDB
|
OLE DB provider for SQL Server
|
|
MSDAORA
|
OLE DB provider for Oracle 7.3 and Oracle 8.
|
|
Microsoft.Jet.OLEDB.4.0
|
OLE DB provider for Access (and other Jet data sources)
|
All OLE DB types are contained in the
System.Data.OleDb namespace (see Table A-4). For low-level information about
OLE DB providers, you can refer to
the OLE DB programmer's reference on MSDN at
http://msdn.microsoft.com/library/en-us/oledb/htm/oledb_providers_overview.asp.
Table A-4. OLE DB .NET provider classes
IDbConnection
|
OleDbConnection
|
IDbCommand
|
OleDbCommand
|
|
IDataParameter, IDbDataParameter
|
OleDbParameter
|
|
IDataReader, IDataRecord
|
OleDbDataReader
|
|
IDataAdapter, IDbDataAdapter
|
OleDbDataAdapter
|
IDbTransaction
|
OleDbTransaction
|
The OLE DB managed provider doesn't include any
structures for OLE DB types. However, the
OleDbDataReader does include additional methods
that allow you to specify the data type when retrieving a column
value. Table A-5 shows the mapping between OLE DB
types and .NET framework types (although it doesn't
include types used exclusively for stored procedure parameters).
Table A-5. OLE DB type mappings
DBTYPE_I8
|
Int64
|
BigInt
|
DBTYPE_BYTES
|
Byte[]
|
Binary
|
DBTYPE_BOOL
|
Boolean
|
Boolean
|
DBTYPE_BSTR
|
String
|
BSTR
|
DBTYPE_STR
|
String
|
Char
|
DBTYPE_CY
|
Decimal
|
Currency
|
DBTYPE_DATE
|
DateTime
|
Date
|
DBTYPE_DBDATE
|
DateTime
|
DBDate
|
DBTYPE_DBTIME
|
TimeSpan
|
DBTime
|
DBTYPE_DBTIMESTAMP
|
DateTime
|
DBTimeStamp
|
DBTYPE_DECIMAL
|
Decimal
|
Decimal
|
DBTYPE_R8
|
Double
|
Double
|
DBTYPE_EMPTY
|
Not applicable
|
Empty
|
DBTYPE_ERROR
|
Exception
|
Error
|
DBTYPE_FILETIME
|
DateTime
|
Filetime
|
DBTYPE_GUID
|
Guid
|
Guid
|
DBTYPE_IDISPATCH
|
Not supported
|
IDispatch
|
DBTYPE_I4
|
Int32
|
Integer
|
DBTYPE_UNKNOWN
|
Not supported
|
IUnknown
|
DBTYPE_NUMERIC
|
Decimal
|
Numeric
|
DBTYPE_PROPVARIANT
|
Object
|
PropVarian
|
DBTYPE_R4
|
Single
|
Single
|
DBTYPE_I2
|
Int16
|
SmallInt
|
DBTYPE_I1
|
SByte
|
TinyInt
|
DBTYPE_UI8
|
UInt64
|
UnsignedBitInt
|
DBTYPE_UI4
|
UInt32
|
UnsignedInt
|
DBTYPE_UI2
|
UInt16
|
UnsignedSmallInt
|
DBTYPE_UI1
|
Byte
|
UnsignedTinyInt
|
DBTYPE_VARIANT
|
Object
|
Variant
|
DBTYPE_WSTR
|
String
|
WChar
|
|
