SAS/ACCESS Software for Relational Databases: Reference

Glossary

	This glossary defines SAS System terms that are used in this book as well as terms that relate specifically to SAS/ACCESS software.
access descriptor	a SAS/ACCESS file, created by using the ACCESS procedure, that describes data to the SAS System that is in a DBMS table. You use an access descriptor as a master descriptor file from which to create view descriptors. See also view and view descriptor.
browsing data	the process of viewing the observations in a file. Depending on how the file is accessed, observations may be viewed one at a time or as a group in a tabular format.
client	in a network, a workstation or application that requests services from a server. See also server.
column	a vertical component of a relational DBMS table. Each column has a unique name and contains data of a specific type and with certain attributes. A column is analogous to a variable in SAS terminology.
column function	an operation that is computed over each value in the column that is named as the argument of the function. For example, AVG(SALARY) is a column function.
commit	the process that ends a transaction and makes permanent any changes to the database that the user made during the transaction. When the commit process occurs, locks on the databse are released so that other applications can access the changed data. The SQL COMMIT statement initiates the commit process. See also rollback.
data type	an attribute of every column in a table. The data type tells the operating system how much physical storage to set aside for the column as well as the type of data that the column contains. It is similar to the type attribute of SAS variables.
data value	in the SAS System, a unit of character or numeric information in a SAS data set. A data value represents one variable in an observation.
database	an organized collection of related data. In most relational DBMSs, a database contains objects such as tables, views, and indexes.
database management system (DBMS)	an integrated software package that enables you to create and manipulate data in the form of databases. See also relational database management system.
DATA step view	a type of SAS data set that consists of a stored DATA step program. Like other SAS data views, a DATA step view contains a definition of data that are stored elsewhere. You create a DATA step view by specifying the VIEW= option in a DATA statement. The view's input data can come from one or more sources, including external files and other SAS data sets. Because a DATA step view only reads (opens for input) other files, you cannot update this view's underlying data. DATA step views can function only as input data sets.
editing data	the process of viewing a file with the ability to change its data. Depending on how the file is accessed, observations may be viewed one at a time or as a group in a tabular format.
engine	a part of the SAS System that reads from or writes to a file. Each engine allows the SAS System to access files that have a particular format. There are several types of engines. See also interface view engine.
file	a collection of related records that are treated as a unit. SAS files are processed and controlled through the SAS System and are stored in a SAS data library.
format	an instruction that the SAS System uses to display or write each value of a variable. Some formats are supplied by SAS software. Other formats can be written by the user with the FORMAT procedure in base SAS software or created using SAS/TOOLKIT software. In SAS/ACCESS software, the default formats vary according to the interface product.
index	(1) in SAS software, a component of a SAS data set that enables the SAS System to access observations in the data set quickly and efficiently. The purpose of SAS indexes is to optimize WHERE-clause processing and to facilitate BY-group processing. (2) a named object that directs the database management system (DBMS) to the storage location of a particular data value for a given column. These indexes are also used to optimize WHERE-clause processing and join processing. Depending on how selection criteria are specified, the SAS System can use DBMS indexes to speed data retrieval.
informat	a pattern that the SAS System uses to determine how values that are entered in variable fields should be interpreted. The SAS System provides a set of standard informats and also enables you to define your own custom informats.
interface view engine	a SAS System engine that retrieves data directly from files that have been formatted by other software vendors.
libref	the name that is temporarily associated with a SAS data library. You assign a libref with a LIBNAME statement or with operating system control language.
member	a SAS file in a SAS data library.
member name	a name that is given to a SAS file in a SAS data library.
member type	a name assigned by the SAS System that identifies the type of information stored in a SAS file. Member types include ACCESS, DATA, CATALOG, PROGRAM, and VIEW.
missing value	a value in the SAS System that indicates that no data are stored in the variable for the current observation. By default, the SAS System represents a missing numeric value with a single period, and a missing character value is represented by a blank space.
observation	the horizontal component of a SAS data file. An observation is a collection of data values that are associated with a single entity, such as a customer or state. Each observation contains one data value for each variable in the data file. An observation is analogous to a row in a DBMS table.
PROC SQL view	a SAS data set (of type VIEW) that is created by the SQL procedure. A PROC SQL view contains no data; instead, it stores the information that is required to read data values from its underlying files, which can include SAS data files, SAS/ACCESS views, DATA step views, or other PROC SQL views. When executed, a PROC SQL view's output can be either a subset or a superset of one or more underlying files. See also view.
query	a request to retrieve data from a data set, DBMS table, or view. Queries are implemented with the PROC SQL SELECT statement.
referential integrity	consistency among related data that are stored in different tables.
relational database management system	a database management system that organizes and accesses data according to relationships between data items. ORACLE and DB2 are examples of relational database management systems.
rollback	in most databases, the process that restores the database to its state when changes were last committed, voiding any recent changes. The SQL ROLLBACK statement initiates the rollback processes. See also commit.
row	the horizontal component of a relational DBMS table. A row is analogous to a SAS observation.
SAS data file	one of the forms of a SAS data set that was implemented in Version 6 of the SAS System. A SAS data file contains both the data values and the descriptor information that is associated with the data, such as the variable attributes. In previous releases of the SAS System, all SAS data sets were SAS data files. SAS data files are of member type DATA. In the SAS System, a PROC SQL table is a SAS data file.
SAS data library	a collection of one or more SAS files that are recognized by the SAS System and that are referenced and stored as a unit. Each file is a member of the library.
SAS data set	(1) descriptor information and its related data values, organized as a table of observations and variables that can be processed by the SAS System. A SAS data set can be either a SAS data file or a SAS data view. (2) in comparison to database management systems, a collection of information that is stored as a unit under the SAS System. A SAS data set is arranged in a rectangular, two-dimensional format. Each item in a SAS data set is called a data value. Data values in a row compose an observation, and those in a column compose a variable. See also SAS data file and SAS data view.
SAS data view	one of the forms of a SAS data set that were implemented in Version 6 of the SAS System. A SAS data view contains only the descriptor and other information that is required to retrieve the data values from other data sources. PROC SQL views, SAS/ACCESS views, and DATA step views are considered SAS data views. SAS data views are of member type VIEW.
SAS Explorer	an interactive, windowing interface to SAS System software. Display manager commands can be issued by typing them on the command line, pressing function keys, or selecting items from the menu facility. Within one session, many different tasks can be accomplished, including preparing and submitting programs, viewing and printing results, and debugging and resubmitting programs.
SAS/ACCESS views	See view descriptor and SAS data view.
server	in a network, a computer or application that is reserved for servicing other computers or applications in the network. Servers can provide file services and communication services, and they enable users to access common resources such as disks, data, and modems. See also client.
SQL Procedure Pass-Through Facility	a group of SQL procedure statements that send and receive data directly between a relational database management system (DBMS) and the SAS System. The Pass-Through facility includes the CONNECT, DISCONNECT, and EXECUTE statements, and the CONNECTION TO component. You must have SAS/ACCESS software installed for the DBMS that you use in order to use the Pass-Through Facility.
Structured Query Language (SQL)	the standardized, high-level query language that is used in relational database management systems to create and manipulate database management system objects. The SAS System implements SQL through the SQL procedure.
table	in general, a two-dimensional system of representing data in rows and columns.
trigger	for some DBMSs, a type of user-defined stored procedure that is executed whenever a user issues a data-modification command such as INSERT, DELETE, or UPDATE for a specified table or column. Triggers can be used to implement referential integrity or to maintain business constraints. See also referential integrity.
variable	a column in a SAS data set. A variable is a set of data values that describe a given characteristic across all observations.
view	a definition of a virtual data set. The definition is named and stored for later use. This file contains no data but describes or defines data that are stored elsewhere. See also DATA step view, PROC SQL view, SAS data view, and view descriptor.
view descriptor	a SAS/ACCESS file that defines all or a subset of the DBMS data that are described by an access descriptor. See also access descriptor.
wildcard character	a character that is used to represent possible characters at a particular position in a word in order to generalize the word.

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