# eXtremeSQL Virtual Tables

> It can be useful to create and manipulate temporary tables for data of a non-permanent nature. Temporary tables in eXtremeSQL are called “Virtual Tables” and have the following advantages:

> - They remain in memory for the duration of the application, or until the database is closed;
> - They can be indexed for sorting and faster access;
> - They are accessed directly like rows from any eXtremeDB database through standard SQL statements;
> - They can be updated just like normal table rows;
> - They can be accessed within a transaction including other eXtremeDB tables.

> Virtual tables are created within an application by instantiating objects sub-classed from the Table class and then providing the table count and a pointer to the tables in the McoSqlOpenParameters passed to the McoSqlEngine method `Open()`.