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

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

All Implemented Interfaces:

org.apache.derby.iapi.sql.compile.Visitable

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public class ColumnReference

extends ValueNode

A ColumnReference represents a column in the query tree. The parser generates a ColumnReference for each column reference. A column refercence could be a column in a base table, a column in a view (which could expand into a complex expression), or a column in a subquery in the FROM clause.

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Field Summary
java.lang.String	columnName
int	columnNumber
private  int	nestingLevel
(package private)  int	origColumnNumber
java.lang.String	origName
(package private)  ResultColumn	origSource
(package private)  int	origTableNumber
private  boolean	replacesAggregate
ResultColumn	source
private  int	sourceLevel
TableName	tableName
int	tableNumber
private  int	tokBeginOffset
private  int	tokEndOffset

 

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

ColumnReference()

 

Method Summary
ValueNode	bindExpression(FromList fromList, SubqueryList subqueryList, java.util.Vector aggregateVector)           Bind this expression.
boolean	categorize(org.apache.derby.iapi.util.JBitSet referencedTabs, boolean simplePredsOnly)           Categorize this predicate.
boolean	constantExpression(PredicateList whereClause)           Return whether or not this expression tree represents a constant value.
void	copyFields(ColumnReference oldCR)           Copy all of the "appropriate fields" for a shallow copy.
void	generateExpression(ExpressionClassBuilder acb, org.apache.derby.iapi.services.compiler.MethodBuilder mb)           ColumnReference's are to the current row in the system.
ValueNode	getClone()           Return a clone of this node.
java.lang.String	getColumnName()           Get the name of this column
int	getColumnNumber()           Get the column number for this ColumnReference.
(package private)  boolean	getCorrelated()           Return whether or not this CR is correlated.
boolean	getGeneratedToReplaceAggregate()           Determine whether or not this node was generated to replace an aggregate in the user's SELECT.
(package private)  int	getNestingLevel()           Get the nesting level for this CR.
protected  int	getOrderableVariantType()           Return the variant type for the underlying expression.
java.lang.String	getSchemaName()           Get the user-supplied schema name of this column.
ResultColumn	getSource()           Get the source this columnReference
(package private)  int	getSourceLevel()           Get the source level for this CR.
ResultColumn	getSourceResultColumn()           Get the source for this ValueNode.
java.lang.String	getSourceSchemaName()           Get the name of the schema for the Column's base table, if any.
java.lang.String	getSourceTableName()           Get the name of the underlying(base) table this column comes from, if any.
java.lang.String	getSQLColumnName()           Get the column name for purposes of error messages or debugging.
java.lang.String	getTableName()           Get the user-supplied table name of this column.
TableName	getTableNameNode()           Return the table name as the node it is.
int	getTableNumber()           Get the table number for this ColumnReference.
(package private)  void	getTablesReferenced(org.apache.derby.iapi.util.JBitSet refs)           Update the table map to reflect the source of this CR.
int	getTokenBeginOffset()           Get the begin offset of the parser token for the column name Will only be set when the CR was generated by the parser.
int	getTokenEndOffset()           Get the end offset of the parser token for the column name.
org.apache.derby.iapi.types.DataTypeDescriptor	getTypeServices()           Get the DataTypeServices from this Node.
void	init(java.lang.Object columnName, java.lang.Object tableName)           Initializer.
void	init(java.lang.Object columnName, java.lang.Object tableName, java.lang.Object tokBeginOffset, java.lang.Object tokEndOffset)           Initializer.
boolean	isCloneable()           Return whether or not this expression tree is cloneable.
void	markGeneratedToReplaceAggregate()           Mark this node as being generated to replace an aggregate.
(package private)  boolean	pointsToColumnReference()           Return whether or not the source of this ColumnReference is itself a ColumnReference.
void	printSubNodes(int depth)           Prints the sub-nodes of this object.
ValueNode	putAndsOnTop()           Do the 1st step in putting an expression into conjunctive normal form.
void	remapColumnReferences()           Remap all of the ColumnReferences in this expression tree to point to the ResultColumn that is 1 level under their current source ResultColumn.
ValueNode	remapColumnReferencesToExpressions()           Remap all ColumnReferences in this tree to be clones of the underlying expression.
void	setColumnName(java.lang.String columnName)           Set the name of this column
(package private)  void	setNestingLevel(int nestingLevel)           Set the nesting level for this CR.
void	setSource(ResultColumn source)           Set the source this columnReference
(package private)  void	setSourceLevel(int sourceLevel)           Set the source level for this CR.
void	setTableNameNode(TableName tableName)
void	setTableNumber(int tableNumber)           Set this ColumnReference to refer to the given table number.
java.lang.String	toString()           Convert this object to a String.
void	unRemapColumnReferences()
boolean	updatableByCursor()           Is the column wirtable by the cursor or not.

 

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

bindExpression, changeToCNF, checkIsBoolean, checkReliability, checkReliability, checkTopPredicatesForEqualsConditions, copyFields, eliminateNots, genEqualsFalseTree, generate, generateFilter, genIsNullTree, genSQLJavaSQLTree, getClause, getConstantValueAsObject, getDataValueFactory, getTablesReferenced, getTransformed, getTypeCompiler, getTypeId, init, isBinaryEqualsOperatorNode, isBooleanFalse, isBooleanTrue, isConstantExpression, isParameterNode, isRelationalOperator, optimizableEqualityNode, preprocess, selectivity, setClause, setDescriptor, setTransformed, setType, 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, isAtomic, isInstanceOf, isSessionSchema, isSessionSchema, makeConstantAction, makeResultDescription, makeTableName, needsSavepoint, nodeHeader, optimize, parseQueryText, printLabel, 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

 

Field Detail

columnName

public java.lang.String columnName

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tableName

public TableName tableName

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tableNumber

public int tableNumber

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columnNumber

public int columnNumber

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source

public ResultColumn source

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origSource

ResultColumn origSource

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origName

public java.lang.String origName

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origTableNumber

int origTableNumber

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origColumnNumber

int origColumnNumber

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replacesAggregate

private boolean replacesAggregate

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nestingLevel

private int nestingLevel

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sourceLevel

private int sourceLevel

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tokBeginOffset

private int tokBeginOffset

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tokEndOffset

private int tokEndOffset

Constructor Detail

ColumnReference

public ColumnReference()

Method Detail

init

public void init(java.lang.Object columnName,
                 java.lang.Object tableName,
                 java.lang.Object tokBeginOffset,
                 java.lang.Object tokEndOffset)

Initializer. This one is called by the parser where we could be dealing with delimited identifiers.

Overrides:

init in class QueryTreeNode

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init

public void init(java.lang.Object columnName,
                 java.lang.Object tableName)

Initializer.

Overrides:

init in class QueryTreeNode

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toString

public java.lang.String toString()

Convert this object to a String. See comments in QueryTreeNode.java for how this should be done for tree printing.

Overrides:

toString in class ValueNode

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printSubNodes

public void printSubNodes(int depth)

Prints the sub-nodes of this object. See QueryTreeNode.java for how tree printing is supposed to work.

Overrides:

printSubNodes in class QueryTreeNode

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getTokenBeginOffset

public int getTokenBeginOffset()

Get the begin offset of the parser token for the column name Will only be set when the CR was generated by the parser.

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getTokenEndOffset

public int getTokenEndOffset()

Get the end offset of the parser token for the column name. Will only be set when the CR was generated by the parser.

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getCorrelated

boolean getCorrelated()

Return whether or not this CR is correlated.

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setNestingLevel

void setNestingLevel(int nestingLevel)

Set the nesting level for this CR. (The nesting level at which the CR appears.)

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getNestingLevel

int getNestingLevel()

Get the nesting level for this CR.

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setSourceLevel

void setSourceLevel(int sourceLevel)

Set the source level for this CR. (The nesting level of the source of the CR.)

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getSourceLevel

int getSourceLevel()

Get the source level for this CR.

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markGeneratedToReplaceAggregate

public void markGeneratedToReplaceAggregate()

Mark this node as being generated to replace an aggregate. (Useful for replacing aggregates in the HAVING clause with column references to the matching aggregate in the user's SELECT.

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getGeneratedToReplaceAggregate

public boolean getGeneratedToReplaceAggregate()

Determine whether or not this node was generated to replace an aggregate in the user's SELECT.

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getClone

public ValueNode getClone()
                   throws org.apache.derby.iapi.error.StandardException

Return a clone of this node.

Overrides:

getClone in class ValueNode

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copyFields

public void copyFields(ColumnReference oldCR)
                throws org.apache.derby.iapi.error.StandardException

Copy all of the "appropriate fields" for a shallow copy.

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bindExpression

public ValueNode bindExpression(FromList fromList,
                                SubqueryList subqueryList,
                                java.util.Vector aggregateVector)
                         throws org.apache.derby.iapi.error.StandardException

Bind this expression. This means binding the sub-expressions, as well as figuring out what the return type is for this expression. NOTE: We must explicitly check for a null FromList here, column reference without a FROM list, as the grammar allows the following: insert into t1 values(c1)

Overrides:

bindExpression in class ValueNode

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getSQLColumnName

public java.lang.String getSQLColumnName()

Get the column name for purposes of error messages or debugging. This returns the column name as used in the SQL statement. Thus if it was qualified with a table, alias name that will be included.

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getColumnName

public java.lang.String getColumnName()

Get the name of this column

Overrides:

getColumnName in class ValueNode

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setColumnName

public void setColumnName(java.lang.String columnName)

Set the name of this column

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getTableNumber

public int getTableNumber()

Get the table number for this ColumnReference.

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setTableNumber

public void setTableNumber(int tableNumber)

Set this ColumnReference to refer to the given table number.

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getTableName

public java.lang.String getTableName()

Get the user-supplied table name of this column. This will be null if the user did not supply a name (for example, select a from t). The method will return B for this example, select b.a from t as b The method will return T for this example, select t.a from t

Overrides:

getTableName in class ValueNode

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getSourceTableName

public java.lang.String getSourceTableName()

Get the name of the underlying(base) table this column comes from, if any. Following example queries will all return T select a from t select b.a from t as b select t.a from t

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getSourceSchemaName

public java.lang.String getSourceSchemaName()
                                     throws org.apache.derby.iapi.error.StandardException

Get the name of the schema for the Column's base table, if any. Following example queries will all return APP (assuming user is in schema APP) select t.a from t select b.a from t as b select app.t.a from t

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updatableByCursor

public boolean updatableByCursor()

Is the column wirtable by the cursor or not. (ie, is it in the list of FOR UPDATE columns list)

Overrides:

updatableByCursor in class ValueNode

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getTableNameNode

public TableName getTableNameNode()

Return the table name as the node it is.

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setTableNameNode

public void setTableNameNode(TableName tableName)

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getColumnNumber

public int getColumnNumber()

Get the column number for this ColumnReference.

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getSource

public ResultColumn getSource()

Get the source this columnReference

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setSource

public void setSource(ResultColumn source)

Set the source this columnReference

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putAndsOnTop

public ValueNode putAndsOnTop()
                       throws org.apache.derby.iapi.error.StandardException

Do the 1st step in putting an expression into conjunctive normal form. This step ensures that the top level of the expression is a chain of AndNodes.

Overrides:

putAndsOnTop in class ValueNode

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categorize

public boolean categorize(org.apache.derby.iapi.util.JBitSet referencedTabs,
                          boolean simplePredsOnly)

Categorize this predicate. Initially, this means building a bit map of the referenced tables for each predicate. If the source of this ColumnReference (at the next underlying level) is not a ColumnReference or a VirtualColumnNode then this predicate will not be pushed down. For example, in: select * from (select 1 from s) a (x) where x = 1 we will not push down x = 1. NOTE: It would be easy to handle the case of a constant, but if the inner SELECT returns an arbitrary expression, then we would have to copy that tree into the pushed predicate, and that tree could contain subqueries and method calls. Also, don't allow a predicate to be pushed down if it contains a ColumnReference that replaces an aggregate. This can happen if the aggregate is in the HAVING clause. In this case, we would be pushing the predicate into the SelectNode that evaluates the aggregate, which doesn't make sense, since the having clause is supposed to be applied to the result of the SelectNode. RESOLVE - revisit this issue once we have views.

Overrides:

categorize in class ValueNode

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remapColumnReferences

public void remapColumnReferences()

Remap all of the ColumnReferences in this expression tree to point to the ResultColumn that is 1 level under their current source ResultColumn. This is useful for pushing down single table predicates. RESOLVE: Once we start pushing join clauses, we will need to walk the ResultColumn/VirtualColumnNode chain for them to remap the references.

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unRemapColumnReferences

public void unRemapColumnReferences()

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getSourceResultColumn

public ResultColumn getSourceResultColumn()

Description copied from class: ValueNode

Get the source for this ValueNode.

Overrides:

getSourceResultColumn in class ValueNode

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remapColumnReferencesToExpressions

public ValueNode remapColumnReferencesToExpressions()
                                             throws org.apache.derby.iapi.error.StandardException

Remap all ColumnReferences in this tree to be clones of the underlying expression.

Overrides:

remapColumnReferencesToExpressions in class ValueNode

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getTablesReferenced

void getTablesReferenced(org.apache.derby.iapi.util.JBitSet refs)

Update the table map to reflect the source of this CR.

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isCloneable

public boolean isCloneable()

Return whether or not this expression tree is cloneable.

Overrides:

isCloneable in class ValueNode

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constantExpression

public boolean constantExpression(PredicateList whereClause)

Description copied from class: ValueNode

Return whether or not this expression tree represents a constant value. In this case, "constant" means that it will always evaluate to the same thing, even if it includes columns. A column is constant if it is compared to a constant expression.

Overrides:

constantExpression in class ValueNode

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generateExpression

public void generateExpression(ExpressionClassBuilder acb,
                               org.apache.derby.iapi.services.compiler.MethodBuilder mb)
                        throws org.apache.derby.iapi.error.StandardException

ColumnReference's are to the current row in the system. This lets us generate a faster get that simply returns the column from the current row, rather than getting the value out and returning that, only to have the caller (in the situations needed) stuffing it back into a new column holder object. We will assume the general generate() path is for getting the value out, and use generateColumn() when we want to keep the column wrapped.

Overrides:

generateExpression in class ValueNode

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getSchemaName

public java.lang.String getSchemaName()

Get the user-supplied schema name of this column. This will be null if the user did not supply a name (for example, select t.a from t). Another example for null return value (for example, select b.a from t as b). But for following query select app.t.a from t, this will return APP Code generation of aggregate functions relies on this method

Overrides:

getSchemaName in class ValueNode

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getOrderableVariantType

protected int getOrderableVariantType()

Return the variant type for the underlying expression. The variant type can be: VARIANT - variant within a scan (method calls and non-static field access) SCAN_INVARIANT - invariant within a scan (column references from outer tables) QUERY_INVARIANT - invariant within the life of a query (constant expressions)

Overrides:

getOrderableVariantType in class ValueNode

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pointsToColumnReference

boolean pointsToColumnReference()

Return whether or not the source of this ColumnReference is itself a ColumnReference.

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getTypeServices

public org.apache.derby.iapi.types.DataTypeDescriptor getTypeServices()

Get the DataTypeServices from this Node.

Overrides:

getTypeServices in class ValueNode

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SUMMARY:  JAVADOC |  SOURCE |  DOWNLOAD | NESTED | FIELD | CONSTR | METHOD	DETAIL: FIELD | CONSTR | METHOD

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