Data Types

The data types and isolation levels supported by the .NET data provider depend on the data store to which you are connecting.

Table 10-1 lists the data types supported by the .NET data provider and how they are mapped to the .NET Framework types. You can use the table to infer the data types that will be used when a DataSet is filled using a DataAdapter. This table also identifies the proper accessors for accessing the data when a DataReader object is used directly.

The SequeLink data type column refers to the native type name.
The SequeLinkDbType column refers to the SequeLink data provider's type enumeration. Generally, there is a one to one mapping between the native type and the SequeLinkDbType.
The .NET Framework Type column refers to the base data types available in the framework.
The .NET Framework Typed Accessor column refers to the method that must be used to access a column of this type when using a DataReader.

Table 10-1. Mapping of SequeLink Data Types  

SequeLink Service Data Type	SequeLinkDbType	.NET Framework Type	.NET Framework Typed Accessor
BIGINT	Bigint	Int64	GetInt64( )
BINARY	Binary	Byte[]	GetBytes( )
BIT	Bit	Boolean	GetBoolean( )
BLOB	Blob	Byte[]	GetBytes( )
CHAR	Char	String	GetString( ) GetChars( )
CLOB	Clob	String	GetString( ) GetChars( )
DATE	Date	DateTime	GetDateTime( )
DECIMAL	Decimal	Decimal	GetDecimal( )
DOUBLE	Double	Double	GetDouble( )
FLOAT	Double	Double	GetDouble( )
GRAPHIC	Char	String	GetString( ) GetChars( )
INTEGER	Int	Int32	GetInt32( )
LONGVARBINARY	LongVarBinary	Byte[]	GetBytes( )
LONGVARCHAR	LongVarChar	String	GetString( ) GetChars( )
NUMBER	Decimal	Decimal	GetDecimal( )
REAL	Single	Single	GetFloat( )
SMALLINT	SmallInt	Int16	GetInt16( )
TIME	Time	TimeSpan	GetValue( )
TIMESTAMP	TimeStamp	DateTime	GetDateTime( )
TINYINT	Byte	Byte[]	GetByte( )
VARBINARY	VarBinary	Byte[]	GetBytes( )
VARCHAR	VarChar	String	GetString( ) GetChars( )
VARGRAPHIC	VarChar	String	GetString( ) GetChars( )

Mapping Parameter Data Types

The type of the parameter is specific to each data provider. The .NET data provider 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 DB type 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 data provider uses the following order when inferring the data type of a parameter:

The data provider uses the provider-specific data type if it has been specified.
The data provider 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 data provider 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 10-2 shows how SequeLink infers its types if only the System.Data.DbType is specified.

Table 10-2. Mapping of the System.Data.DbTypes to SequeLinkDbTypes  

System.Data.DbType	SequeLinkDbType
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	BigInt
Object	Not supported
Sbyte	Byte
Single	Single
String	VarChar
StringFixedLength	Char
Time	Time
Uint16	Int
Uint32	Decimal
Uint64	Decimal
VarNumeric	Not supported

Table 10-3 shows the mapping that the data provider uses to infer a data type if neither the provider-specific data type or the System.Data.DbType are provided.

Table 10-3. Mapping .NET Framework Data Types to SequeLinkDbTypes  

.NET Framework Type	SequeLinkDbType
Boolean	Bit
Byte	Byte
Byte[]	Varbinary
Char, Char[]	Not supported
DateTime	TimeStamp
Decimal	Decimal
Double	Double
Guid	Not supported
Int16	SmallInt
Int32	Int
Int64	BigInt
Object	Not supported
Single	Single
String	VarChar
Timespan	Time
Uint16	Int
Uint32	Decimal
Uint64	Decimal