Module org.apache.derby.engine
Package org.apache.derby.vti

## Class Restriction

- java.lang.Object
- - org.apache.derby.vti.Restriction

- All Implemented Interfaces:
    `Serializable`
  Direct Known Subclasses:
    `Restriction.AND`, `Restriction.ColumnQualifier`, `Restriction.OR`

      public abstract class Restriction
      extends Object
      implements Serializable

  An expression to be pushed into a Table Function so that the Table Function can short-circuit its processing and return fewer rows. A restriction is represented as a binary tree. The non-leaf nodes are ANDs and ORs. The leaf nodes are ColumnQualifiers. A ColumnQualifier is a simple expression comparing a constant value to a column in the Table Function.

  See Also:
    Serialized Form

- - ### Nested Class Summary

    Nested Classes
    Modifier and Type | Class | Description
    --- | --- | ---
    `static class` | `Restriction.AND` | An AND of two Restrictions
    `static class` | `Restriction.ColumnQualifier` | A simple comparison of a column to a constant value.
    `static class` | `Restriction.OR` | An OR of two Restrictions

  - ### Constructor Summary

    Constructors
    Constructor | Description
    --- | ---
    `Restriction()` |

  - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `abstract String` | `toSQL()` | Turn this Restriction into a string suitable for use in a WHERE clause.

    - ### Methods inherited from class java.lang.Object

      `equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Constructor Detail

    - #### Restriction

          public Restriction()

  - ### Method Detail

    - #### toSQL

          public abstract String toSQL()

      Turn this Restriction into a string suitable for use in a WHERE clause.
      Returns:
        this Restriction as a string suitable for use in a WHERE clause.