Data Types for OLE DB

Overview

Each data source column in a table has a name and a data type. The data type tells the data source how much physical storage to set aside for the column and the form in which the data is stored. This section includes information about OLE DB null and default values and data conversions.

OLE DB Null Values

Many relational database management systems have a special value called NULL. A DBMS NULL value means an absence of information and is analogous to a SAS missing value. When SAS/ACCESS reads a DBMS NULL value, it interprets it as a SAS missing value.

In most relational databases, columns can be specified as NOT NULL so that they require data (they cannot contain NULL values). When a column is specified as NOT NULL, the DBMS does not add a row to the table unless the row has a value for that column. When creating a DBMS table with SAS/ACCESS, you can use the DBNULL= data set option to indicate whether NULL is a valid value for specified columns.

OLE DB mirrors the behavior of the underlying DBMS with regard to NULL values. See the documentation for your DBMS for information about how it handles NULL values.

For more information about how SAS handles NULL values, see Potential Result Set Differences When Processing Null Data.

To control how the DBMS handles SAS missing character values, use the NULLCHAR= and NULLCHARVAL= data set options.

Specifying the BOOL_VAL Environment Variable

By default, the SAS/ACCESS LIBNAME engine imports YES (TRUE) into SAS as the numeric value 1. Set the environment variable with this statement.

/* To have the YES value imported into SAS as numeric value-1 */
OPTIONS SET=BOOL_VAL ASIS;

/* Reset to the default value */
OPTIONS SET=BOOL_VAL SAS;

LIBNAME Statement Data Conversions

This table shows all data types and default SAS formats that SAS/ACCESS Interface to OLE DB supports. It does not explicitly specify the data types as they exist for each data source. It lists the types that each data source's data type might map to. For example, an INTEGER data type under DB2 might map to an OLE DB data type of DBTYPE_I4. All data types are supported.

The following table shows the default data types that SAS/ACCESS Interface to OLE DB uses when creating DBMS tables. SAS/ACCESS Interface to OLE DB lets you specify non-default data types by using the DBTYPE= data set option.