# Package org.apache.cayenne.query

Defines standard queries supported by Cayenne and extension mechanism to create custom queries.

See: Description

- Interface Summary
  Interface | Description
  --- | ---
  EmbeddableResultSegment |
  EntityResultSegment | A "compiled" version of a `EntityResult` descriptor.
  ParameterizedQuery | Defines a query that can serve as a template for other queries.
  PrefetchProcessor | A hierarchical visitor interface for traversing a tree of PrefetchTreeNodes.
  Query | Defines minimal API of a query descriptor that is executable via Cayenne.
  QueryMetadata | Provides a common interface for accessing query metadata.
  QueryRouter | An interface used by Queries to route themselves to an appropriate QueryEngine.
  ScalarResultSegment |
  Select<T> | A common interface for grouping together different kinds of queries that return results.
  SelectById.IdSpec |
  SelectById.QueryRoot |
  SQLAction | Defines API for query execution strategy over JDBC connection (as in Strategy Pattern).
  SQLActionVisitor | A factory interface to create standard SQLActions for a set of standard queries.

- Class Summary
  Class | Description
  --- | ---
  AbstractMappedQuery |
  AbstractQuery | A common superclass of Cayenne queries.
  BatchQuery | BatchQuery and its descendants allow to group similar data for the batch database modifications, including inserts, updates and deletes.
  BatchQueryRow | Represents a single row of values in a BatchQuery.
  CacheableQuery | Shared functionality for cacheable queries.
  ColumnSelect<T> | A helper builder for queries selecting individual properties based on the root object.
  DefaultEmbeddableResultSegment |
  DeleteBatchQuery | Batched delete query.
  EJBQLQuery | An EJBQL query representation in Cayenne.
  FluentSelect<T> | Base class for `ObjectSelect` and `ColumnSelect`
  IndirectQuery | A base superclass for queries that resolve into some other queries during the routing phase.
  InsertBatchQuery | Batched INSERT query.
  MappedExec | A query that represents a named parameterized non selecting query stored in the mapping.
  MappedSelect<T> | A query that represents a named parameterized selecting query stored in the mapping.
  ObjectIdQuery | A query that matches zero or one object or data row corresponding to the ObjectId.
  ObjectSelect<T> | A selecting query providing chainable API.
  Ordering | Defines object sorting criteria, used either for in-memory sorting of object lists or as a specification for building ORDER BY clause of a SelectQuery query.
  Orderings | Orderings is provided so that you can chain Ordering together and then use the result to pass into methods that require List<Ordering>
  PrefetchSelectQuery<T> | A SelectQuery to perform a prefetch based on another query.
  PrefetchTreeNode | Defines a node in a prefetch tree.
  ProcedureCall<T> | Fluent API for calling stored procedures.
  ProcedureQuery | A query based on Procedure.
  QueryChain | A Query decorator for a collection of other queries.
  QueryMetadataProxy |
  RefreshQuery | A query that allows to explicitly clear both object and list caches either via refetch (eager refresh) or invalidate (lazy refresh).
  RelationshipQuery | A query that selects objects related to a given object via a mapped relationship.
  SelectById<T> | A query to select objects by id.
  SelectById.MultiMapIdSpec |
  SelectById.MultiScalarIdSpec |
  SelectById.SingleMapIdSpec |
  SelectById.SingleScalarIdSpec |
  SelectQuery<T> | Deprecated since 4.2, use `ObjectSelect`
  SQLExec | A generic query based on raw SQL and featuring fluent API.
  SQLSelect<T> | A selecting query based on raw SQL and featuring fluent API.
  SQLTemplate | A query that executes unchanged (except for template preprocessing) "raw" SQL specified by the user.
  SQLTemplateMetadata |
  UpdateBatchQuery | Batched UPDATE query.

- Enum Summary
  Enum | Description
  --- | ---
  CapsStrategy | Defines forced capitalization of the result column names in the DataRow.
  QueryCacheStrategy | Defines query result caching policy.
  SortOrder | Constants to order query results (the ORDER BY clause).

## Package org.apache.cayenne.query Description

Defines standard queries supported by Cayenne and extension mechanism to create custom queries. Many of the queries in this package are used by the framework internally. Normally users would only care about these general query classes:

- SelectQuery
- SQLTemplate
- ProcedureQuery

and sometimes - these specialized queries:

- QueryChain
- RelationshipQuery
- SingleObjectQuery

Cayenne can "execute" any object as a query as long as it implements Query interface and provides meaningful implementation of either Query.route(...) and/or Query.createSQLAction(SQLActionVisitor)} methods. So users can extend/customize queries if they need to. Custom implementations would normally either create a query from a standard Cayenne set and delegate the execution to it (acting as a sort of "query builder"), or can implement its own non-standard SQLAction.

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