org.apache.derby.impl.sql.compile
Class CurrentRowLocationNode

java.lang.Object
  org.apache.derby.impl.sql.compile.QueryTreeNode
      org.apache.derby.impl.sql.compile.ValueNode
          org.apache.derby.impl.sql.compile.CurrentRowLocationNode

All Implemented Interfaces:

Visitable

public class CurrentRowLocationNode

extends ValueNode

The CurrentRowLocation operator is used by DELETE and UPDATE to get the RowLocation of the current row for the target table. The bind() operations for DELETE and UPDATE add a column to the target list of the SelectNode that represents the ResultSet to be deleted or updated.

Field Summary

Fields inherited from class org.apache.derby.impl.sql.compile.ValueNode

clause, dataTypeServices, IN_HAVING_CLAUSE, IN_SELECT_LIST, IN_UNKNOWN_CLAUSE, IN_WHERE_CLAUSE, transformed

Fields inherited from class org.apache.derby.impl.sql.compile.QueryTreeNode

AUTOINCREMENT_INC_INDEX, AUTOINCREMENT_IS_AUTOINCREMENT_INDEX, AUTOINCREMENT_START_INDEX, beginOffset, endOffset

Constructor Summary

CurrentRowLocationNode()

Method Summary

ValueNode	bindExpression(FromList fromList, SubqueryList subqueryList, java.util.Vector aggregateVector) Binding this expression means setting the result DataTypeServices.
void	generateExpression(ExpressionClassBuilder acb, MethodBuilder mbex) CurrentRowLocationNode is used in updates and deletes.

Methods inherited from class org.apache.derby.impl.sql.compile.ValueNode

bindExpression, categorize, changeToCNF, checkIsBoolean, checkReliability, checkReliability, checkTopPredicatesForEqualsConditions, constantExpression, copyFields, eliminateNots, genEqualsFalseTree, generate, generateFilter, genIsNullTree, genSQLJavaSQLTree, getClause, getClone, getColumnName, getConstantValueAsObject, getDataValueFactory, getOrderableVariantType, getSchemaName, getSourceResultColumn, getTableName, getTablesReferenced, getTransformed, getTypeCompiler, getTypeId, getTypeServices, init, isBinaryEqualsOperatorNode, isBooleanFalse, isBooleanTrue, isCloneable, isConstantExpression, isParameterNode, isRelationalOperator, optimizableEqualityNode, preprocess, putAndsOnTop, remapColumnReferencesToExpressions, selectivity, setClause, setDescriptor, setTransformed, setType, toString, updatableByCursor, verifyChangeToCNF, verifyEliminateNots, verifyPutAndsOnTop

Methods inherited from class org.apache.derby.impl.sql.compile.QueryTreeNode

accept, bind, convertDefaultNode, debugFlush, debugPrint, executeSchemaName, executeStatementName, formatNodeString, foundString, generate, generateAuthorizeCheck, getBeginOffset, getClassFactory, getCompilerContext, getContextManager, getCursorInfo, getDataDictionary, getDependencyManager, getEndOffset, getExecutionFactory, getGenericConstantActionFactory, getIntProperty, getLanguageConnectionContext, getNodeFactory, getNodeType, getNullNode, getParameterTypes, getRowEstimate, getSchemaDescriptor, getSchemaDescriptor, getSPSName, getStatementType, getTableDescriptor, getTypeCompiler, init, init, init, init, init, init, init, init, init, init, init, init, init, isAtomic, isInstanceOf, isSessionSchema, isSessionSchema, makeConstantAction, makeResultDescription, makeTableName, needsSavepoint, nodeHeader, optimize, parseQueryText, printLabel, printSubNodes, referencesSessionSchema, resolveTableToSynonym, setBeginOffset, setContextManager, setEndOffset, setNodeType, setRefActionInfo, treePrint, treePrint, verifyClassExist

Methods inherited from class java.lang.Object

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

Constructor Detail

CurrentRowLocationNode

public CurrentRowLocationNode()

Method Detail

bindExpression

public ValueNode bindExpression(FromList fromList,
                                SubqueryList subqueryList,
                                java.util.Vector aggregateVector)
                         throws StandardException

Binding this expression means setting the result DataTypeServices. In this case, the result type is always the same.

Overrides:

bindExpression in class ValueNode

Parameters:

fromList - The FROM list for the statement. This parameter is not used in this case.

subqueryList - The subquery list being built as we find SubqueryNodes

aggregateVector - The aggregate vector being built as we find AggregateNodes

Returns:

The new top of the expression tree.

Throws:

StandardException - Thrown on error

generateExpression

public void generateExpression(ExpressionClassBuilder acb,
                               MethodBuilder mbex)
                        throws StandardException

CurrentRowLocationNode is used in updates and deletes. See generate() in UpdateNode and DeleteNode to get the full overview of generate(). This class is responsible for generating the method that will return the RowLocation for the next row to be updated or deleted. This routine will generate a method of the form: private SQLRef fieldx; ... public DataValueDescriptor exprx() throws StandardException { return fieldx = ( "result set member".getRowLocation(), fieldx); } and return the generated code: exprx() ("result set member" is a member of the generated class added by UpdateNode or DeleteNode.) This exprx function is used within another exprx function, and so doesn't need a static field or to be public; but at present, it has both. fieldx is a generated field that is initialized to null when the activation is constructed. getSQLRef will re-use fieldx on calls after the first call, rather than allocate a new SQLRef for each call.

Overrides:

generateExpression in class ValueNode

Parameters:

acb - The ExpressionClassBuilder for the class being built

mbex - The method the expression will go into

Throws:

StandardException - Thrown on error