By default, Stonefield Query uses a SQLite database named SQData.dat in the App_Data folder for security tables as well as tags and formulas; this is specified in the Provider for Stonefield Query Data and Conn. String for Stonefield Query Data configuration settings. However, you can use a different database engine if you wish. The connection settings are defined in ApplicationSettings.xml in the App_Data folder. Here are the defaults:

<configuration>
  <connectionStrings>
    <add name="security" connectionString="Data Source=SQData.dat" 
      providerName="System.Data.SQLite" />
    <add name="formulas" connectionString="Data Source=SQData.dat" 
      providerName="System.Data.SQLite" />
    <add name="tags" connectionString="Data Source=SQData.dat" 
      providerName="System.Data.SQLite" />
  </connectionStrings>
</configuration>

The "security" connection string is used for the security tables, "formulas" is for formulas, and "tags" is for tags.

To use a different database engine, change the connection strings as necessary. For example, for Microsoft SQL Server, use something like:

<configuration>
  <connectionStrings>
    <add name="security" connectionString="server=MyServer;database=MyDatabase;
      uid=username;pwd=password" providerName="System.Data.SqlClient" />
    <add name="formulas" connectionString="server=MyServer;database=MyDatabase;
      uid=username;pwd=password" providerName="System.Data.SqlClient" />
    <add name="tags" connectionString="server=MyServer;database=MyDatabase;
      uid=username;pwd=password" providerName="System.Data.SqlClient" />
  </connectionStrings>
</configuration>

You can either edit ApplicationSettings.xml or change the Provider for Stonefield Query Data and Conn. String for Stonefield Query Data configuration settings. Note that if you're not using SQLite or some other database engine that automatically creates a database if necessary when it connects (for example, SQL Server doesn't), you'll have to create the database manually before running Stonefield Query for the first time. Stonefield Query automatically creates the tables in the database.