org.eclipse.persistence.queries
Class ValueReadQuery

java.lang.Object
  org.eclipse.persistence.queries.DatabaseQuery
      org.eclipse.persistence.queries.ReadQuery
          org.eclipse.persistence.queries.DataReadQuery
              org.eclipse.persistence.queries.DirectReadQuery
                  org.eclipse.persistence.queries.ValueReadQuery

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable

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.

See Also:

Serialized Form

Author:

James Sutherland

Since:

TOPLink/Java 1.2

Field Summary

Fields inherited from class org.eclipse.persistence.queries.DirectReadQuery

valueConverter

Fields inherited from class org.eclipse.persistence.queries.DataReadQuery

containerPolicy, useAbstractRecord

Fields inherited from class org.eclipse.persistence.queries.ReadQuery

fetchSize, firstResult, maxRows, queryId, queryResultCachingPolicy, temporaryCachedQueryResults

Fields inherited from class org.eclipse.persistence.queries.DatabaseQuery

accessor, arguments, argumentTypeNames, argumentTypes, argumentValues, CascadeAggregateDelete, CascadeAllParts, CascadeByMapping, CascadeDependentParts, cascadePolicy, CascadePrivateParts, descriptor, doNotRedirect, executionSession, flushOnExecute, hintString, isCustomQueryUsed, isExecutionClone, isFromParseCache, isNativeConnectionRequired, isPrepared, isUserDefined, name, NoCascading, properties, queryMechanism, queryTimeout, redirector, session, sessionName, shouldBindAllParameters, shouldCacheStatement, shouldCloneCall, shouldMaintainCache, shouldPrepare, shouldUseWrapperPolicy, translationRow

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	executeDatabaseQuery() INTERNAL: Execute the query.
boolean	isValueReadQuery() PUBLIC: Return if this is a value read query.

Methods inherited from class org.eclipse.persistence.queries.DirectReadQuery

buildObject, executeNonCursor, getValueConverter, isDirectReadQuery, setValueConverter

Methods inherited from class org.eclipse.persistence.queries.DataReadQuery

cacheResult, clone, execute, getContainerPolicy, isDataReadQuery, prepare, prepareForExecution, remoteExecute, setContainerPolicy, setUseAbstractRecord, useCollectionClass, useCursoredStream, useCursoredStream, useCursoredStream, useScrollableCursor, useScrollableCursor, useScrollableCursor

Methods inherited from class org.eclipse.persistence.queries.ReadQuery

cacheQueryResults, clearQueryResults, clonedQueryExecutionComplete, copyFromQuery, doNotCacheQueryResults, getFetchSize, getFirstResult, getMaxRows, getQueryId, getQueryResults, getQueryResults, getQueryResults, getQueryResultsCachePolicy, getTemporaryCachedQueryResults, isDefaultPropertiesQuery, isReadQuery, remoteExecute, setFetchSize, setFirstResult, setMaxRows, setQueryId, setQueryResults, setQueryResults, setQueryResultsCachePolicy, setTemporaryCachedQueryResults, shouldCacheQueryResults

Methods inherited from class org.eclipse.persistence.queries.DatabaseQuery

addArgument, addArgument, addArgument, addArgumentByTypeName, addArgumentValue, addArgumentValues, addCall, addStatement, bindAllParameters, buildSelectionCriteria, cacheStatement, cascadeAllParts, cascadeByMapping, cascadeOnlyDependentParts, cascadePrivateParts, checkDescriptor, checkEarlyReturn, checkForCustomQuery, checkPrepare, checkPrepare, convertClassNamesToClasses, dontBindAllParameters, dontCacheStatement, dontCascadeParts, dontMaintainCache, executeInUnitOfWork, extractRemoteResult, getAccessor, getArguments, getArgumentTypeNames, getArgumentTypes, getArgumentValues, getCall, getCascadePolicy, getDatasourceCall, getDatasourceCalls, getDefaultRedirector, getDescriptor, getDomainClassNounName, getDoNotRedirect, getEJBQLString, getExecutionSession, getFlushOnExecute, getHintString, getJPQLString, getName, getProperties, getProperty, getQueryMechanism, getQueryNounName, getQueryTimeout, getRedirector, getReferenceClass, getReferenceClassName, getSelectionCriteria, getSensorName, getSession, getSessionName, getShouldBindAllParameters, getSQLStatement, getSQLString, getSQLStrings, getTranslatedSQLString, getTranslatedSQLStrings, getTranslationRow, hasAccessor, hasArguments, hasProperties, hasQueryMechanism, hasSessionName, ignoreBindAllParameters, ignoreCacheStatement, isCallQuery, isCascadeOfAggregateDelete, isCustomQueryUsed, isCustomSelectionQuery, isDataModifyQuery, isDeleteAllQuery, isDeleteObjectQuery, isExecutionClone, isExpressionQuery, isFromParseCache, isInsertObjectQuery, isModifyAllQuery, isModifyQuery, isNativeConnectionRequired, isObjectBuildingQuery, isObjectLevelModifyQuery, isObjectLevelReadQuery, isPrepared, isReadAllQuery, isReadObjectQuery, isReportQuery, isSQLCallQuery, isUpdateAllQuery, isUpdateObjectQuery, isUserDefined, isWriteObjectQuery, maintainCache, prepareCall, prepareCustomQuery, prepareForRemoteExecution, prepareFromQuery, redirectQuery, removeProperty, replaceValueHoldersIn, rowFromArguments, setAccessor, setArguments, setArgumentTypeNames, setArgumentTypes, setArgumentValues, setCall, setCascadePolicy, setDatasourceCall, setDescriptor, setDoNotRedirect, setEJBQLString, setExecutionSession, setFlushOnExecute, setHintString, setIsCustomQueryUsed, setIsExecutionClone, setIsFromParseCache, setIsNativeConnectionRequired, setIsPrepared, setIsUserDefined, setJPQLString, setName, setProperties, setProperty, setQueryMechanism, setQueryTimeout, setRedirector, setSelectionCriteria, setSession, setSessionName, setShouldBindAllParameters, setShouldBindAllParameters, setShouldCacheStatement, setShouldMaintainCache, setShouldPrepare, setShouldUseWrapperPolicy, setSQLStatement, setSQLString, setTranslationRow, shouldBindAllParameters, shouldCacheStatement, shouldCascadeAllParts, shouldCascadeByMapping, shouldCascadeOnlyDependentParts, shouldCascadeParts, shouldCascadePrivateParts, shouldCloneCall, shouldIgnoreBindAllParameters, shouldIgnoreCacheStatement, shouldMaintainCache, shouldPrepare, shouldUseWrapperPolicy, toString

Methods inherited from class java.lang.Object

equals, finalize, 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. Warning: Allowing an unverified SQL string to be passed into this method makes your application vulnerable to SQL injection attacks.

ValueReadQuery

public ValueReadQuery(Call call)

PUBLIC: Initialize the query to use the specified call.

Method Detail

executeDatabaseQuery

public java.lang.Object executeDatabaseQuery()
                                      throws DatabaseException

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

Overrides:

executeDatabaseQuery in class DataReadQuery

Returns:

Object the data value or null.

Throws:

DatabaseException - an error has occurred on the database

isValueReadQuery

public boolean isValueReadQuery()

PUBLIC: Return if this is a value read query.

Overrides:

isValueReadQuery in class DatabaseQuery