SQL/MP Installation and Management Guide

The SQL/MP Database Management Environment
HP NonStop SQL/MP Installation and Management Guide—523353-004
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SQL Objects
be part of more than one database. Each node (system) can have more than one SQL
database, and a database can span more than one node.
You use SQL/MP through SQL statements, SQLCI commands, and SQL compiler
directives.
SQL Objects
An SQL/MP database includes these objects:
•
One or more base tables
•
Indexes on tables
•
Views on tables
•
Constraints on tables
•
Collations used by tables, indexes, and views
Base Tables
A base table is a table of one or more columns for which rows of data are stored in a
file. The base table definition specifies the physical characteristics of the table for the
file system. Column definitions for the table specify data types and character sets for
row values.
Data is entered into the table, one row at a time. Each row contains a value for each
table column. Stored data is retrieved and displayed in columns and rows.
The order in which rows are stored in a file is determined by the table organization and
the table’s primary key. The table organization can be key-sequenced, entry-
sequenced, or relative, and the file organization corresponds to the table organization
explained in Understanding SQL File Structures on page 3-1. Primary keys are defined
as follows:
•
The primary key of a table stored in a key-sequenced file is one or more columns
defined by the user, and the SQL/MP software, or solely by the SQL/MP software.
•
The primary key of a table stored in a relative file is a relative record number
defined by the user or the SQL/MP software.
•
The primary key for a table stored in an entry-sequenced file is a record address
defined by the SQL/MP software.
Indexes
An index is an alternate access path to a table (alternate key) that differs from the
primary access path (primary key). An SQL/MP index, stored in a file, includes
columns for the table’s primary key and the alternate key.