Data Types

Table 2-2 lists the data types supported by the Pervasive.SQL 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 Pervasive Data Type column refers to the native type name.

The PsqlDbType column refers to the Pervasive.SQL data provider's type enumeration. Generally, there is a one to one mapping between the native type and the PsqlDbType. The Pervasive NUMBER data type, which can be either a decimal or a double, is an exception to this rule.

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 2-2 Mapping of Pervasive Data Types
Pervasive Data Type	PsqlDbType	.NET Framework Type	.NET Framework Typed Accessor
BFLOAT4	BFloat4	Single	GetSingle()
BFLOAT8	BFloat8	Double	GetDouble()
BIGINT	BigInt	Int64	GetDecimal()
BINARY	Binary	Byte[]	GetBytes( )
BIT	Bit	Byte[]	GetBytes( )
CHAR	Char	String Char[]	GetString( ) GetChars( )
CURRENCY	Currency	Decimal	GetDecimal( )
DATE	Date	DateTime	GetDateTime()
DECIMAL	Decimal	Decimal	GetDecimal()
DOUBLE	Double	Double	GetDouble()
IDENTITY	Identity	Int32	GetInt32()
INTEGER	Integer	Int32	GetInt32( )
LONGVARBINARY	LongVarBinary	Byte[]	GetBytes( )
LONGVARCHAR	LongVarChar	Byte[]	GetBytes( )
NUMERIC	Decimal	Decimal	GetDecimal( )
NUMERICSA	DecimalSA	Decimal	GetDecimal( )
NUMERICSTS	DecimalSTS	Decimal	GetDecimal( )
REAL	Real	Single	GetSingle( )
SMALLIDENTITY	SmallIdentity	Int16	GetInt16( )
SMALLINT	SmallInt	Int16	GetInt16( )
TIME	Time	Timespan	GetValue()
TIMESTAMP	Timestamp	DateTime	GetDateTime()
TINYINT	TinyInt	SByte	GetByte( )
UBIGINT	UBigInt	UInt64	GetUInt64()
UINTEGER	UInteger	UInt32	GetUInt32( )
USMALLINT	USmallInt	UInt16	GetUInt16( )
UTINYINT	UTinyInt	Byte	GetByte( )
VARCHAR	VarChar	String Char[]	GetString( ) GetChars( )

Mapping Parameter Data Types

The type of the parameter is specific to each data provider. The Pervasive.SQL 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 Pervasive.SQL 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 2-3 shows how Pervasive.SQL infers its types if only the System.Data.DbType is specified.

Table 2-3 Mapping System.Data.DbTypes to PsqlDbTypes
System.Data.DbType	PsqlDbType
AnsiString	VarChar
AnsiStringFixedLength	Char
Binary	Binary
Boolean	Integer
Byte	Integer
Currency	Currency
Date	Date
DateTime	Timestamp
Decimal	Decimal
Double	Double
Int16	SmallInt
Int32	Integer
Int64	BigInt
Sbyte	Integer
Single	BFloat4
String	VarChar
StringFixedLength	Char
Time	Time
Uint16	USmallInt
Uint32	UInteger
Uint64	UBigInt
VarNumeric	Decimal

Table 2-4 shows the mapping that the data provider uses to infer a data type if neither the provider-specific data type nor the System.Data.DbType are provided.

Table 2-4 Mapping .NET Framework Types to PsqlDbTypes
.NET Framework Type	PsqlDbType
Boolean	Integer
Byte	Integer
Byte[]	Binary
DateTime	Timestamp
Decimal	Decimal
Double	Double
Int16	SmallInt
Int32	Integer
Int64	BigInt
Single	BFloat4
String	VarChar
Uint16	USmallInt
Uint32	UInteger
Uint64	UBigInt

Data Types Supported With Stream Objects

The Pervasive.SQL data provider supports the use of streams as inputs to long data parameters with the data types listed in Table 2-5.

Table 2-5 Supported Stream Objects
Provider Data Type	Stream Type Supported
LONGVARBINARY	Stream
LONGVARCHAR	TextReader

See Using Streams as Input to Long Data Parameters for a discussion of using streams.