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| SAS/ACCESS Interface to ODBC |
Data Types for ODBC
| Overview |
Every column in a table has a name and a data type. The data type tells the DBMS how much physical storage to set aside for the column and the form in which the data is stored. This section includes information about ODBC null and default values and data conversions.
| ODBC 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 defined as NOT NULL so that they require data (they cannot contain NULL values). When a column is defined 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.
ODBC 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 SAS missing character values are handled by the DBMS, use the NULLCHAR= and NULLCHARVAL= data set options.
| LIBNAME Statement Data Conversions |
This table shows all data types and default SAS formats that SAS/ACCESS Interface to ODBC supports. It does not explicitly define the data types as they exist for each DBMS. It lists the SQL types that each DBMS data type would map to. For example, a CHAR data type under DB2 would map to an ODBC data type of SQL_CHAR. All data types are supported.
| ODBC Data Type | Default SAS Format |
|---|---|
| SQL_CHAR | $n |
| SQL_VARCHAR | $n |
| SQL_LONGVARCHAR | $n |
| SQL_BINARY | $n.* |
| SQL_VARBINARY | $n.* |
| SQL_LONGVARBINARY | $n.* |
| SQL_DECIMAL | m or m.n or none if m and n are not specified |
| SQL_NUMERIC | m or m.n or none if m and n are not specified |
| SQL_INTEGER | 11. |
| SQL_SMALLINT | 6. |
| SQL_TINYINT | 4. |
| SQL_BIT | 1. |
| SQL_REAL | none |
| SQL_FLOAT | none |
| SQL_DOUBLE | none |
| SQL_BIGINT | 20. |
| SQL_INTERVAL | $n |
| SQL_GUID | $n |
| SQL_TYPE_DATE | DATE9. |
| SQL_TYPE_TIME | TIME8. |
| SQL_TYPE_TIMESTAMP | DATETIMEm.n where m and n depend on precision |
| * Because the ODBC driver does the conversion, this field displays as if the $HEXn. format were applied. | |
The following table shows the default data types that SAS/ACCESS Interface to ODBC uses when creating tables.SAS/ACCESS Interface to ODBC lets you specify non-default data types by using the DBTYPE= data set option.
| SAS Variable Format | Default ODBC Data Type |
|---|---|
| m.n | SQL_DOUBLE or SQL_NUMERIC using m.n if the DBMS allows it |
| $n. | SQL_VARCHAR using n |
| datetime formats | SQL_TIMESTAMP |
| date formats | SQL_DATE |
| time formats | SQL_TIME |
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Copyright © 2010 by SAS Institute Inc., Cary, NC, USA. All rights reserved.