Since TIBCO Spotfire Server uses JDBC drivers to connect to data sources in Information Services via Information Links, it is often useful diagnostically to test a connection or query using the same JDBC driver outside of Spotfire. If there are still issues connecting to a data source or in the query execution when using a 3rd party tool like DbVisualizer, then the issue is in the driver's connection to the database and not within Spotfire. If there are no issues connecting or executing the query in the 3rd party tool, then Spotfire and its configuration should be investigated more closely.
You can test connections with any 3rd party tool, but this article uses DbVisualizer version 9.2.3. DbVisualizer has many JDBC drivers installed by default, but often you will either need to test with a specific .jar version or with a .jar file that is not included in DbVisualizer. This article describes how to configure DbVisualizer to use a custom JDBC driver .jar file.