The LIBNAME Statement for Relational Databases

Overview of the LIBNAME Statement for Relational Databases

The SAS/ACCESS LIBNAME statement extends the SAS global LIBNAME statement to enable you to assign a libref to a relational DBMS. This feature lets you reference a DBMS object directly in a DATA step or SAS procedure. You can use it to read from and write to a DBMS object as if it were a SAS data set. You can associate a SAS libref with a relational DBMS database, schema, server, or group of tables and views. This section specifies the syntax of the SAS/ACCESS LIBNAME statement and provides examples. For details about the syntax, see LIBNAME Statement Syntax for Relational Databases.

Sorting Data

When you use the SAS/ACCESS LIBNAME statement to associate a libref with relational DBMS data, you might observe some behavior that differs from that of normal SAS librefs. Because these librefs refer to database objects, such as tables and views, they are stored in the format of your DBMS. DBMS format differs from the format of normal SAS data sets. This is helpful to remember when you access and work with DBMS data.

For example, you can sort the observations in a normal SAS data set and store the output to another data set. However, in a relational DBMS, sorting data often has no effect on how it is stored. Because you cannot depend on your data to be sorted in the DBMS, you must sort the data at the time of query. Furthermore, when you sort DBMS data, the results might vary depending on whether your DBMS places data with NULL values (which are translated in SAS to missing values) at the beginning or the end of the result set.

Using SAS Functions

When you use librefs that refer to DBMS data with SAS functions, some functions might return a value that differs from what is returned when you use the functions with normal SAS data sets. For example, the PATHNAME function might return a blank value. For a normal SAS libref, a blank value means that the libref is not valid. However, for a libref associated with a DBMS object, a blank value means only that there is no pathname associated with the libref.

Usage of some functions might also vary. For example, the LIBNAME function can accept an optional SAS-data-library argument. When you use the LIBNAME function to assign or de-assign a libref that refers to DBMS data, you omit this argument. For full details about how to use SAS functions, see the SAS Language Reference: Dictionary.

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