GLOSSARY - Concepts of Database Management - page 373

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Save See backup .
Scalability The ability of a computer system to con-
tinue to function well as utilization of the system
increases.
SEC Rule 17a-4 The rule of the Security and
Exchange Commission that specifies the retention
requirements of all electronic communications and
records for financial and investment entities.
Second normal form (2NF) A relation is in second
normal form if it is in first normal form and no non-
key attribute is dependent on only a portion of the
primary key.
Secondary key A column (attribute) or collection of
columns that is of interest for retrieval purposes (and
that is not already designated as some other type
of key).
Secondary sort key When sorting on two fields, the
less important field; also called minor sort key .
Security The prevention of unauthorized access to
the database.
SELECT The relational algebra command to select
rows from a table. Also, the retrieval command
in SQL.
SELECT clause The part of an SQL SELECT com-
mand that indicates the columns to be included in the
query results.
Server A computer that provides services to the cli-
ents in a client/server system; also called a back-end
processor or a back-end machine .
Server-side extension Instructions executed by a
Web server to provide dynamic Web page capability.
These extensions are usually contained in separate
files that are referenced within the HTML documents.
Server-side script See server-side extension.
Session The duration of a Web client's connection to
a Web server.
SGML See Standard Generalized Markup
Language .
Shared lock A lock that lets other users read locked
data.
Shrinking phase A phase during a database update
in which the DBMS releases all the locks previously
acquired for a transaction and acquires no new locks.
Simple condition A condition that involves only a
single field and a single value.
Single-column index See single-field index .
Single-field index An index built on a single field
(column).

Slice and dice In a data warehouse, selecting por-
tions of the available data, or reducing the data cube.
SMALLINT The SQL data type for integer data for
small integers.
Smart card Small plastic cards about the size of a
driver's license that have built-in circuits containing
processing logic to identify the cardholder.
Sort The process of arranging rows in a table or
results of a query in a particular order.
Sort key The field on which data are sorted; also
called a key .
SQL See Structured Query Language .
Standard Generalized Markup Language (SGML)
A metalanguage used to create document markup
languages; SGML became a standard in 1986. Lan-
guages based on the full SGML are used to manage
large, complex reports and technical specifications for
a variety of computer platforms, printers, and other
devices.
Star schema A multidimensional database whose
conceptual shape resembles a star.
Stateless A condition for a communication protocol,
such as HTTP, in which the connection between the
sender and the receiver, such as a Web server and a
Web client, is closed once the sender responds to the
sender's request and the sender retains no information
about the request or the sender.
Statement history The area of memory in MySQL
that stores the most recently entered command.
Static Web page A Web page that displays the exact
same content for all Web clients.
Stored procedure A file containing a collection of
compiled and optimized SQL statements that are
available for future use.
Structured Query Language (SQL) A very popular
relational data definition and manipulation language
that is used in many relational DBMSs.
Stylesheet A document that specifies how to process
the data contained in another document and present
the data in a Web browser, in a printed report, on a
mobile device, in a sound device, or in other presenta-
tion media.
Subclass A class that inherits the structure and
methods of another class and for which you can define
additional attributes and methods.
Subquery In SQL, a query that appears within
another query.
SUBTRACT The relational algebra command for per-
forming the difference of two tables.