# Package org.apache.torque

Torque is an object-relational mapper for Java. In other words, Torque lets you access and manipulate data in a relational database using java objects. Unlike most other object-relational mappers, Torque does not use reflection to access user-provided classes, but it generates the necessary classes (including the Data Objects) from an XML schema describing the database layout (which can either be written by hand or generated from an existing database). The XML schema can also be used to generate and execute a SQL script which creates all the tables in the database.

- Interface Summary
  Interface | Description
  --- | ---
  Column | The metadata of a column (or pseudocolumn) in a database.

- Class Summary
  Class | Description
  --- | ---
  ColumnImpl | An implementation of the column interface.
  Database | Bundles all information about a database.
  Torque | A static facade wrapper around the Torque implementation (which is in `TorqueInstance`).
  TorqueInstance | The core of Torque's implementation.

- Exception Summary
  Exception | Description
  --- | ---
  ConstraintViolationException | This exception is thrown if a database operation violates a database constraint, e.g. a foreign key constraint, a unique constraint or a not-null constraint.
  DeadlockException | This exception is thrown if the database detects a deadlock.
  NoRowsException | This exception indicates that no rows were returned but at least one should have been returned.
  OptimisticLockingFailedException | This exception is thrown if the database detects that a row in a table with optimistic locking was updated by another process.
  TooManyRowsException | This exception indicates that more rows were returned than expected.
  TorqueException | The base class of all checked exceptions thrown by Torque.
  TorqueRuntimeException | This is the base class of all non-checked exceptions in Torque.