The number of connections needed will depend on how many data sources will be accessed and how many simultaneous queries will be used.
Multiple data sources
If the template must access two or more different sources of data, you must specify at least one connection for each data source.
For example, if the template must access both an Oracle database and a Microsoft Access database, you must specify at least one Oracle database connection and one Microsoft Access database connection.
Another example is a template that must access two databases in Microsoft SQL Server. In this case, you must specify at least two SQL Server data sources – one for each database.
Performing two or more queries on the same data source
If any data source will be accessed by two or more simultaneous queries – such as an outer query and an inner query – a separate connection must be specified for each query.
For example, you may want to use the results of a SELECT query on a database table to insert, update, or delete records from several tables in that database. You can set up one connection for the SELECT query and a second connection for the INSERT, UPDATE or DELETE query.
For more details on how to work with multiple queries, see Working with multiple SQL statements.
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Specifying connection information and testing the connection