oracle.toplink.queryframework
Class ValueReadQuery

java.lang.Object
oracle.toplink.queryframework.DatabaseQuery
oracle.toplink.queryframework.ReadQuery
oracle.toplink.queryframework.DataReadQuery
oracle.toplink.queryframework.DirectReadQuery
oracle.toplink.queryframework.ValueReadQuery

All Implemented Interfaces:

java.lang.Cloneable, oracle.toplink.internal.helper.FalseUndefinedTrue, java.io.Serializable

public class ValueReadQuery

extends DirectReadQuery

Purpose: Concrete class to perform a read of a single data value.

Responsibilities: Used in conjunction with CursoredStream size and Platform getSequence. This can be used to read a single data value (i.e. one field). A single data value is returned, or null if no rows are returned.

Since:

TOPLink/Java 1.2

See Also:

Serialized Form

Field Summary

Fields inherited from class oracle.toplink.queryframework.DatabaseQuery

CascadeAggregateDelete, CascadeAllParts, CascadeDependentParts, CascadePrivateParts, NoCascading, QUERY_PREPARE

Fields inherited from interface oracle.toplink.internal.helper.FalseUndefinedTrue

False, True, Undefined

Constructor Summary

ValueReadQuery()
PUBLIC: Initialize the state of the query.

ValueReadQuery(Call call)
PUBLIC: Initialize the query to use the specified call.

ValueReadQuery(java.lang.String sqlString)
PUBLIC: Initialize the query to use the specified SQL string.

Method Summary

java.lang.Object

execute() INTERNAL: Execute the query.

Methods inherited from class oracle.toplink.queryframework.DirectReadQuery

buildObject, executeNonCursor

Methods inherited from class oracle.toplink.queryframework.DataReadQuery

clone, getContainerPolicy, isDataReadQuery, prepareForExecution, remoteExecute, setContainerPolicy, useCollectionClass, useCursoredStream, useCursoredStream, useCursoredStream, useScrollableCursor, useScrollableCursor, useScrollableCursor

Methods inherited from class oracle.toplink.queryframework.ReadQuery

cacheQueryResults, clearQueryResults, doNotCacheQueryResults, execute, getMaxRows, getQueryId, isReadQuery, remoteExecute, setMaxRows, setQueryId, setShouldCacheQueryResults, shouldCacheQueryResults

Methods inherited from class oracle.toplink.queryframework.DatabaseQuery

addArgument, addArgument, addArgument, addArgumentValue, addArgumentValues, addCall, addStatement, bindAllParameters, cacheStatement, cascadeAllParts, cascadeOnlyDependentParts, cascadePrivateParts, checkEarlyReturn, checkPrepare, dontBindAllParameters, dontCacheStatement, dontCascadeParts, dontMaintainCache, extractRemoteResult, getAccessor, getArguments, getArgumentTypes, getArgumentValues, getCall, getCascadePolicy, getDescriptor, getEJBQLString, getHintString, getName, getProperties, getProperty, getQueryMechanism, getQueryTimeout, getRedirector, getReferenceClass, getSelectionCriteria, getSession, getSessionName, getSQLStatement, getSQLString, getTranslatedSQLString, getTranslationRow, hasAccessor, hasProperties, hasSessionName, ignoreBindAllParameters, ignoreCacheStatement, isCallQuery, isCascadeOfAggregateDelete, isDataModifyQuery, isDeleteObjectQuery, isExpressionQuery, isModifyQuery, isObjectLevelModifyQuery, isObjectLevelReadQuery, isReadAllQuery, isReadObjectQuery, isReportQuery, isSQLCallQuery, isUserDefined, isWriteObjectQuery, maintainCache, prepareCall, redirectQuery, remoteExecute, removeProperty, replaceValueHoldersIn, rowFromArguments, setAccessor, setArguments, setArgumentTypes, setArgumentValues, setCall, setCascadePolicy, setDescriptor, setEJBQLString, setHintString, setIsUserDefined, setName, setProperties, setProperty, setQueryTimeout, setRedirector, setSelectionCriteria, setSession, setSessionName, setShouldBindAllParameters, setShouldCacheStatement, setShouldMaintainCache, setShouldPrepare, setShouldUseWrapperPolicy, setSQLStatement, setSQLString, setTranslationRow, shouldBindAllParameters, shouldCacheStatement, shouldCascadeAllParts, shouldCascadeOnlyDependentParts, shouldCascadeParts, shouldCascadePrivateParts, shouldIgnoreBindAllParameters, shouldIgnoreCacheStatement, shouldIgnoreMaintainCache, shouldMaintainCache, shouldPrepare, shouldUseWrapperPolicy, toString

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

ValueReadQuery

public ValueReadQuery()

PUBLIC: Initialize the state of the query.

ValueReadQuery

public ValueReadQuery(java.lang.String sqlString)

PUBLIC: Initialize the query to use the specified SQL string.

ValueReadQuery

public ValueReadQuery(Call call)

PUBLIC: Initialize the query to use the specified call.

Method Detail

execute

public java.lang.Object execute()
                         throws DatabaseException

INTERNAL: Execute the query. Perform the work to execute the SQL string.

Overrides:

execute in class DataReadQuery

Returns:

Object the data value or null.

Throws:

DatabaseException - an error has occurred on the database