Projections (Hibernate API Documentation) - Hibernate 3.2.3 正式版 API 英文文档

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org.hibernate.criterion
Class Projections

java.lang.Object
  org.hibernate.criterion.Projections

public final class Projections
extends Object

The criterion package may be used by applications as a framework for building new kinds of Projection. However, it is intended that most applications will simply use the built-in projection types via the static factory methods of this class.

The factory methods that take an alias allow the projected value to be referred to by criterion and order instances.

Author:: Gavin King
See Also:: Criteria, factory methods for Criterion instances

Method Summary

static Projection alias(Projection projection, String alias)
          Assign an alias to a projection, by wrapping it

static AggregateProjection avg(String propertyName)
          A property average value

static CountProjection count(String propertyName)
          A property value count

static CountProjection countDistinct(String propertyName)
          A distinct property value count

static Projection distinct(Projection proj)
          Create a distinct projection from a projection

static PropertyProjection groupProperty(String propertyName)
          A grouping property value

static IdentifierProjection id()
          A projected identifier value

static AggregateProjection max(String propertyName)
          A property maximum value

static AggregateProjection min(String propertyName)
          A property minimum value

static ProjectionList projectionList()
          Create a new projection list

static PropertyProjection property(String propertyName)
          A projected property value

static Projection rowCount()
          The query row count, ie.

static Projection sqlGroupProjection(String sql, String groupBy, String[] columnAliases, Type[] types)
          A grouping SQL projection, specifying both select clause and group by clause fragments

static Projection sqlProjection(String sql, String[] columnAliases, Type[] types)
          A SQL projection, a typed select clause fragment

static AggregateProjection sum(String propertyName)
          A property value sum

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

distinct

public static Projection distinct(Projection proj)

Create a distinct projection from a projection

projectionList

public static ProjectionList projectionList()

Create a new projection list

rowCount

public static Projection rowCount()

The query row count, ie. count(*)

count

public static CountProjection count(String propertyName)

A property value count

countDistinct

public static CountProjection countDistinct(String propertyName)

A distinct property value count

max

public static AggregateProjection max(String propertyName)

A property maximum value

min

public static AggregateProjection min(String propertyName)

A property minimum value

avg

public static AggregateProjection avg(String propertyName)

A property average value

sum

public static AggregateProjection sum(String propertyName)

A property value sum

sqlProjection

public static Projection sqlProjection(String sql,
                                       String[] columnAliases,
                                       Type[] types)

A SQL projection, a typed select clause fragment

sqlGroupProjection

public static Projection sqlGroupProjection(String sql,
                                            String groupBy,
                                            String[] columnAliases,
                                            Type[] types)

A grouping SQL projection, specifying both select clause and group by clause fragments

groupProperty

public static PropertyProjection groupProperty(String propertyName)

A grouping property value

property

public static PropertyProjection property(String propertyName)

A projected property value

id

public static IdentifierProjection id()

A projected identifier value

alias

public static Projection alias(Projection projection,
                               String alias)

Assign an alias to a projection, by wrapping it