A Data Type Conversion

Oracle maps the ANSI data types through ODBC interfaces to supported Oracle data types. When the results of a query are returned, Oracle converts the ODBC data types to Oracle data types.

The tables in this appendix show how Oracle maps ANSI data types through ODBC interfaces to supported Oracle data types when it is retrieving data from a non-Oracle system.

This appendix contains the following table:

• Table A-1, "Mapping ANSI Data Types to Oracle Data Types Through an ODBC Interface"

A.1 Mapping ANSI Data Types to Oracle Data Types Through an ODBC Interface

The Oracle Database Gateway for ODBC maps the data types used in ODBC-compliant data sources to supported Oracle data types. When the results of a query are returned, the Oracle database converts the ODBC data types to Oracle data types. For example, the ODBC data type SQL_TIMESTAMP are converted to Oracle's DATE data type.

If a table contains a column whose data type is not supported by Oracle Database Gateway for ODBC, the column information is not returned to the Oracle database.

Table A-1 maps ODBC data types into equivalent ANSI and Oracle data types. In some cases equivalence to ANSI data types is not guaranteed to be exact because the ANSI SQL standard delegates definition of numeric precision and maximum length of character data to individual implementations. This table reflects a probable mapping between ANSI and ODBC data types for a typical implementation of ANSI SQL .

Table A-1 Mapping ANSI Data Types to Oracle Data Types Through an ODBC Interface

ANSI	ODBC	Oracle
NUMERIC(19,0)	SQL_BIGINT	NUMBER(19,0)
N/A	SQL_BINARY	RAW
CHAR	SQL_CHAR	CHAR
DATE	SQL_DATE	DATE
DECIMAL(p,s)	SQL_DECIMAL(p,s)	NUMBER(p,s)
DOUBLE PRECISION	SQL_DOUBLE	FLOAT(53)
FLOAT	SQL_FLOAT	FLOAT(53)
INTEGER	SQL_INTEGER	NUMBER(10) Note: It is possible under some circumstance for the INTEGER ANSI data type to map to Precision 38, but it usually maps to Precision 10.
N/A	SQL_LONGVARBINARY	LONG RAW
N/A	SQL_LONGVARCHAR	LONG Note: If an ANSI SQL implementation defines a large value for the maximum length of VARCHAR data, it is possible that ANSI VARCHAR will map to SQL_LONGVARCHAR and Oracle LONG. The same is true for OLE DB DBTYPE_STRING (long attribute).
REAL	SQL_REAL	FLOAT(24)
SMALLINT	SQL_SMALLINT	NUMBER(5)
TIME	SQL_TYPE_TIME	CHAR(15)
TIMESTAMP	SQL_TYPE_TIMESTAMP	DATE
NUMERIC(3,0)	SQL_TINYINT	NUMBER(3)
VARCHAR	SQL_VARCHAR	VARCHAR2
BOOLEAN	SQL_BIT	NUMBER(3)