User's Guide
   PART 4. Database Administration and Advanced Use
     CHAPTER 28. Accessing Remote Data       

Basic concepts

This section describes the basic concepts required to access remote data.

  Remote table mappings

Adaptive Server Anywhere presents tables to a client application as if all the data in the tables were stored in the database to which the application is connected. Internally, when a query involving remote tables is executed, the storage location is determined, and the remote location is accessed so that data can be retrieved.

To have remote tables appear as local tables to the client, you create local proxy tables that map to the remote data.

  To create a proxy table:

1. Define the server where the remote data is located. This specifies the type of server and location of the remote server.

        For more information, see Working with remote servers.

2. Map the local user login information to the remote server user login information if the logins on the two servers are different.

        For more information, see Working with external logins.

3. Create the proxy table definition. This specifies the mapping of a local proxy table to the remote table. This includes the server where the remote table is located, and the database name, owner name, table name, and column names of the remote table.

        For more information, see Working with proxy tables.

Administering remote table mappings 

To manage remote table mappings and remote server definitions, you can either use Sybase Central (Java Edition) or you can use a tool such as Interactive SQL and execute the SQL statements directly.

  Server classes

A server class is assigned to each remote server. The server class specifies the access method used to interact with the server. Different types of remote servers require different access methods. The server classes provide Adaptive Server Anywhere detailed server capability information. Adaptive Server Anywhere adjusts its interaction with the remote server based on those capabilities.

There are currently two groups of server classes. The first is JDBC-based; the second is ODBC-based.

The JDBC-based server classes are:

• asajdbc     for Adaptive Server Anywhere (version 6 and later)

• asejdbc     for Adaptive Server Enterprise and SQL Server (version 10 and later)

The ODBC-based server classes are:

• asaodbc     for Adaptive Server Anywhere (version 5.5 and later)

• aseodbc     for Adaptive Server Enterprise and SQL Server (version 10 and later)

• db2odbc     for IBM DB2

• mssodbc     for Microsoft SQL Server

• oraodbc     for Oracle servers (version 8.0 and later)

• odbc     for all other ODBC data sources

     For a full description of remote server classes, see Server Classes for Remote Data Access.