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7.7.8.Supported Conversions

Before the consumer creates an accessor, it can call IConvertType::CanConvert to determine if the provider supports a particular conversion.

Default Data Type Mapping

The OpenLink Provider binds to the ODBC/UDBC data source using the types in the table below. The SQL type is queried using SQLDescribeCol. The sign of the data type (signed/unsigned) is determined using SQLColAttributes. It is used in deciding which C type to use in internal buffers and which type indicator to return through IColumnsInfo::GetColumnInfo.

Table7.4.OLE-DB Data Type Mappings

SQL Type Indicator Indicator of C Type Used For Internal Buffers OLE DB Type Indicator

SQL_CHAR,

SQL_VARCHAR,

SQL_LONGVARCHAR,

SQL_DECIMAL,

SQL_NUMERIC

SQL_C_CHAR

DBTYPE_STR

SQL_BIT

SQL_C_BIT

DBTYPE_BOOL

SQL_TINYINT,

SQL_SMALLINT

SQL_C_USHORT,

SQL_C_SSHORT

DBTYPE_I2

SQL_INTEGER

SQL_C_ULONG,

SQL_C_SLONG

DBTYPE_I4

SQL_BIGINT

SQL_C_STR

DBTYPE_STR

SQL_REAL

SQL_C_FLOAT

DBTYPE_R4

SQL_FLOAT,

SQL_DOUBLE

SQL_C_DOUBLE

DBTYPE_R8

SQL_BINARY,

SQL_VARBINARY,

SQL_LONGVARBINARY

SQL_C_BINARY

DBTYPE_BYTES

SQL_DATE

SQL_C_DATE

DBTYPE_DATE

SQL_TIME

SQL_C_TIME

DBTYPE_DATE

SQL_TIMESTAMP

SQL_C_TIMESTAMP

DBTYPE_DATE

Length Binding

For types DBTYPE_UI1, DBTYPE_I2, DBTYPE_I4, DBTYPE_I8, DBTYPE_R4, DBTYPE_R8, DBTYPE_CY, DBTYPE_NUMERIC, the length binding is always set to the fixed size of the destination binding type, rather than the internal source type.

Supported Data Conversions

The follwoing table outlines the supported type conversion implemented in the OpenLink provider. An 'X' means supported, and '-' means not supported.

Table7.5.OLE-DB Data Type Conversions

I1 I2 I4 I8 UI1 UI2 UI4 UI8 R4 R8 CY DEC NUM BOOL DATE DBDATE DBTIMESTAMP DBTIME BYTES BSTR STR WSTR DISP UNK GUID

I1

X

X

X

X

X

X

X

X

X

X

X

X

X

-

-

-

-

-

X

X

X

X

-

-

-

I2

X

X

X

X

X

X

X

X

X

X

X

X

X

-

-

-

-

-

X

X

X

X

-

-

-

I4

X

X

X

X

X

X

X

X

X

X

X

X

X

-

-

-

-

-

X

X

X

X

-

-

-

I8

X

X

X

X

X

X

X

X

X

X

X

X

X

-

-

-

-

-

X

X

X

X

-

-

-

UI1

X

X

X

X

X

X

X

X

X

X

X

X

X

-

-

-

-

-

X

X

X

X

-

-

-

UI2

X

X

X

X

X

X

X

X

X

X

X

X

X

-

-

-

-

-

X

X

X

X

-

-

-

UI4

X

X

X

X

X

X

X

X

X

X

X

X

X

-

-

-

-

-

X

X

X

X

-

-

-

UI8

X

X

X

X

X

X

X

X

X

X

X

X

X

-

-

-

-

-

X

X

X

X

-

-

-

R4

X

X

X

X

X

X

X

X

X

X

X

X

X

-

-

-

-

-

X

X

X

X

-

-

-

R8

X

X

X

X

X

X

X

X

X

X

X

X

X

-

-

-

-

-

X

X

X

X

-

-

-

CY

X

X

X

X

X

X

X

X

X

X

X

X

X

-

-

-

-

-

X

X

X

X

-

-

-

DEC

X

X

X

X

X

X

X

X

X

X

X

X

X

-

-

-

-

-

X

X

X

X

-

-

-

NUM

X

X

X

X

X

X

X

X

X

X

X

X

X

-

-

-

-

-

X

X

X

X

-

-

-

BOOL

-

-

-

-

-

-

-

-

-

-

-

-

-

X

-

-

-

-

X

X

X

X

-

-

-

DATE

-

-

-

-

-

-

-

-

-

-

-

-

-

-

X

X

X

X

X

X

X

X

-

-

-

DBDATE

-

-

-

-

-

-

-

-

-

-

-

-

-

-

X

X

-

X

X

X

X

X

-

-

-

DBTIME

-

-

-

-

-

-

-

-

-

-

-

-

-

-

X

-

X

X

X

X

X

X

-

-

-

DBTIMESTAMP

-

-

-

-

-

-

-

-

-

-

-

-

-

-

X

X

X

X

X

X

X

X

-

-

-

BYTES

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

-

X

X

X

X

X

X

X

X

BSTR

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

-

-

X

STR

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

-

X

X

WSTR

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

-

X

X

DISP

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

X

-

-

-

X

X

-

UNK

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

X

-

-

-

-

X

-

GUID

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

X

X

X

X

-

-

X

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