SQL Navigator for Oracle 7.6 - User Guide

A database link allows access to a username on a remote database through the local database. A public database link (which only a DBA can create) allows the remote database access to all users of the local database.

The characteristics and usage of this database object are described in Oracle documentation.

An index is a sorted map of selected columns in a table or object. Therefore an index is similar to a table, and the columns in an index refer to the rows and columns of the associated table. By indexing columns frequently used in queries, you can improve data retrieval performance.

An index can be either unique or non-unique.

• A unique index validates every new or changed row in a table for a unique value in the column(s) in the index.
• A non-unique index allows duplicate values in rows.

A non-unique index often enables faster queries.

Oracle8 supports a type of index called a bitmap index. A bitmap index uses a compressed bit-stream storage technique that allows very fast retrieval.

The characteristics and usage of this database object are described in Oracle documentation.

A nested table type is an unordered set of elements. The elements may be built-in datatypes or user-defined types. You can view a nested table as a single-column table or, if the nested table is an object type, as a multicolumn table, with a column representing each attribute of the object type.

A nested table definition does not allocate space. It defines a datatype, which can then be used to declare:

• columns of a relational table
• object type attributes
• PL/SQL variables, parameters, and function return values.

When a nested table appears as the type of a column in a relational table or as an attribute of the underlying object type of an object table, Oracle stores all of the nested table data in a single table, which it associates with the enclosing relational or object table.

The characteristics and usage of this database object are described in Oracle documentation.

A profile is a set of limits on the use of database resources that can be applied to a user. If you assign the profile to a user, that user cannot exceed those limits. If a user exceeds a limit, Oracle aborts and rolls back the transaction, and then ends the session. Profile settings include connect time, password lifetime and reuse, idle time, and similar restrictions.

The characteristics and usage of this database object are described in Oracle documentation.