Mapping Parameter Data Types

The type of the parameter is specific to each data provider. The .NET Client must convert the parameter value to a native format before sending it to the server. The best way for an application to describe a parameter is to use the data provider-specific type enumeration.

In generic programming circumstances, the data provider-specific type may not be available. When no provider-specific DbType has been specified, the data type will be inferred from either the System.Data.DbType or from the .NET Framework type of the parameter’s value.

• The .NET Client infers the data type from the System.Data.DbType if it has been specified, but the provider-specific data type has not been specified.

• The .NET Client infers the data type from the .NET Framework type if neither the provider-specific data type nor the System.Data.DbType have been specified.

Table 30: Mapping of the System.Data.DbTypes to OpenAccessDbTypes
System.Data.DbType	OpenAccessDbType
AnsiString	VarChar
AnsiStringFixedLength	Char
Binary	VarBinary
Boolean	Bit
Byte	Byte
Currency	Decimal
Date	Date
DateTime	TimeStamp
Decimal	Decimal
Double	Double
Guid	Not supported
Int16	SmallInt
Int32	Int
Int64	Not supported
Object	Not supported
Sbyte	Byte
Single	Single
String	VarChar
StringFixedLength	Char
Time	Time
Uint16	Int
Uint32	Decimal
Uint64	Decimal
VarNumeric	Not supported

The following table shows the mapping that the .NET Client uses to infer a data type if neither the provider-specific data type or the System.Data.DbType are provided.

Table 31: Mapping .NET Framework Data Types to OpenAccessDbTypes
.NET Framework Type	OpenAccessDbType
Boolean	Bit
Byte	Byte
Byte[]	Varbinary
Char, Char[]	Not supported
DateTime	TimeStamp
Decimal	Decimal
Double	Double
Guid	Not supported
Int16	SmallInt
Int32	Int
Int64	Not supported
Object	Not supported
Single	Single
String	VarChar
Timespan	Time
Uint16	Int
Uint32	Decimal
Uint64	Decimal