doc.FAQ.HowCanIHelpAnEvaluatorAssessHisDataAccessNeeds Use the following series of questions to help you resolve your data access needs:Do you need to:Category 1. Query a database with one or more client applications? Category 2. Query two or more heterogeneous databases simultaneously? Category 3. Migrate data from one DBMS to another? If you fall into Category 1, you require our UDA drivers If you fall into Category 2, you require our Virtuoso suiteFor category 3, we recommend the Virtuoso suite. Alternatively, if you are using an existing Data Migration tool such as Oracle HS services, UDA is what you require as these drivers work in conjunction with other data migration utilities such as Ms SQLServer's DTS Wizard.Does OpenLink provide Single-Tier or Multi-Tier drivers for the evaluator's DBMS?Category 1 - Yes. Category 2 - No. Evaluators in Category 1 may use the appropriate UDA driver for your database. If you fall into the second Category, you may use OpenLink 's generic ODBC UDA drivers. Both the generic Single-Tier and Multi-Tier ODBC drivers connect to 3rd-party Data Sources, which allow connectivity to your DBMS.Does your evaluator have the database native client?Category 1 - Yes. It is installed on the same machine as the client application. Category 2 - Yes. It is installed on a different machine on the network. Category 3 - No. For evaluators who fall into the Category 1, we recommend the OpenLink Single-Tier drivers. We recommend OpenLink 's Multi-Tier drivers to evaluators in Category 2Evaluators in Category 3 must install the OpenLink server components on their database server.NOTE:Evaluators in Category 2 may install the OpenLink server components on their database server or any machine, which contains the database native client. In this scenario, the OpenLink database agent can connect to the database through that database client. Please see the technical article on connecting via in a three-tier environment