com.akiban.sql.parser
Class ResultColumn

java.lang.Object
  com.akiban.sql.parser.QueryTreeNode
      com.akiban.sql.parser.ValueNode
          com.akiban.sql.parser.ResultColumn

All Implemented Interfaces:

Visitable

Direct Known Subclasses:

AllResultColumn

public class ResultColumn
extends ValueNode

A ResultColumn represents a result column in a SELECT, INSERT, or UPDATE statement. In a SELECT statement, the result column just represents an expression in a row being returned to the client. For INSERT and UPDATE statements, the result column represents an column in a stored table. So, a ResultColumn has to be bound differently depending on the type of statement it appears in.

The type of the ResultColumn can differ from its underlying expression, for example in certain joins the ResultColumn can be nullable even if its underlying column is not. In an INSERT or UPDATE the ResultColumn will represent the type of the column in the table, the type of the underlying expresion will be the type of the source of the value to be insert or updated. The method columnTypeAndLengthMatch() can be used to detect when normalization is required between the expression and the tyoe of ResultColumn. This class does not implement any type normalization (conversion), this is typically handled by a NormalizeResultSetNode.

Field Summary

Fields inherited from class com.akiban.sql.parser.QueryTreeNode

AUTOINCREMENT_CREATE_MODIFY, AUTOINCREMENT_INC_INDEX, AUTOINCREMENT_IS_AUTOINCREMENT_INDEX, AUTOINCREMENT_START_INDEX

Constructor Summary

ResultColumn()

Method Summary

void	adjustVirtualColumnId(int adjust) Adjust the virtualColumnId for this ResultColumn by the specified amount
void	copyFrom(QueryTreeNode node) Fill this node with a deep copy of the given node.
int	getColumnPosition()
ValueNode	getExpression() Get the expression in this ResultColumn.
String	getName() The following methods implement the ResultColumnDescriptor interface.
ColumnReference	getReference()
String	getSchemaName() This returns the user-supplied schema name of the column.
String	getTableName() This returns the user-supplied table name of the column.
TableName	getTableNameObject()
int	getVirtualColumnId() Get the virtualColumnId for this ResultColumn
void	init(Object arg1, Object arg2) Different types of initializer parameters indicate different types of initialization.
boolean	isDefaultColumn() Returns TRUE if the ResultColumn is standing in for a DEFAULT keyword in an insert/update statement.
boolean	isEquivalent(ValueNode o) Tests if this node is equivalent to the specified ValueNode.
boolean	isNameGenerated() Is the name for this ResultColumn generated?
void	printSubNodes(int depth) Prints the sub-nodes of this object.
void	setDefaultColumn(boolean value)
void	setExpression(ValueNode expression) Set the expression in this ResultColumn.
void	setName(String name) Set the name in this ResultColumn.
void	setNameGenerated(boolean value) Set that this result column name is generated.
void	setVirtualColumnId(int id) Set the virtualColumnId for this ResultColumn
String	toString() Convert this object to a String.

Methods inherited from class com.akiban.sql.parser.ValueNode

getColumnName, getSourceResultColumn, getType, getTypeId, init, isBinaryEqualsOperatorNode, isBooleanFalse, isBooleanTrue, isConstantExpression, isInListProbeNode, isParameterNode, isRelationalOperator, isSameNodeType, setNullability, setType

Methods inherited from class com.akiban.sql.parser.QueryTreeNode

accept, convertDefaultNode, debugFlush, debugPrint, formatNodeString, getBeginOffset, getDebugOutput, getEndOffset, getNodeFactory, getNodeType, getNullNode, getParserContext, getStatementType, getUserData, init, init, init, init, init, init, init, init, init, init, init, init, isInstanceOf, makeTableName, makeTableName, nodeHeader, printLabel, setBeginOffset, setDebugOutput, setEndOffset, setNodeType, setParserContext, setUserData, stackPrint, treePrint, treePrint, treePrint

Methods inherited from class java.lang.Object

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

Constructor Detail

ResultColumn

public ResultColumn()

Method Detail

init

public void init(Object arg1,
                 Object arg2)
          throws StandardException

Different types of initializer parameters indicate different types of initialization. Parameters may be:

• arg1 The name of the column, if any.
• arg2 The expression this result column represents

- OR -

• arg1 a column reference node
• arg2 The expression this result column represents

- OR -

• arg1 The column descriptor.
• arg2 The expression this result column represents

- OR -

• dtd The type of the column
• expression The expression this result column represents

Overrides:

init in class QueryTreeNode

Throws:

StandardException - Thrown on error

copyFrom

public void copyFrom(QueryTreeNode node)
              throws StandardException

Fill this node with a deep copy of the given node.

Overrides:

copyFrom in class ValueNode

Throws:

StandardException

isDefaultColumn

public boolean isDefaultColumn()

Returns TRUE if the ResultColumn is standing in for a DEFAULT keyword in an insert/update statement.

setDefaultColumn

public void setDefaultColumn(boolean value)

getName

public String getName()

The following methods implement the ResultColumnDescriptor interface. See the Language Module Interface for details.

getSchemaName

public String getSchemaName()
                     throws StandardException

Description copied from class: ValueNode

This returns the user-supplied schema name of the column. At this class level, it simply returns null. But, the subclasses of ValueNode will overwrite this method to return the user-supplied schema name. When the value node is in a result column of a select list, the user can request metadata information. The result column won't have a column descriptor, so we return some default information through the expression. This lets expressions that are simply columns return all of the info, and others use this supertype's default values.

Overrides:

getSchemaName in class ValueNode

Returns:

the default schema name for an expression -- null

Throws:

StandardException

getTableName

public String getTableName()

Description copied from class: ValueNode

This returns the user-supplied table name of the column. At this class level, it simply returns null. But, the subclasses of ValueNode will overwrite this method to return the user-supplied table name. When the value node is in a result column of a select list, the user can request metadata information. The result column won't have a column descriptor, so we return some default information through the expression. This lets expressions that are simply columns return all of the info, and others use this supertype's default values.

Overrides:

getTableName in class ValueNode

Returns:

the default table name for an expression -- null

getColumnPosition

public int getColumnPosition()

setExpression

public void setExpression(ValueNode expression)

Set the expression in this ResultColumn. This is useful in those cases where you don't know the expression in advance, like for INSERT statements with column lists, where the column list and SELECT or VALUES clause are parsed separately, and then have to be hooked up.

Parameters:

expression - The expression to be set in this ResultColumn

getExpression

public ValueNode getExpression()

Get the expression in this ResultColumn.

Returns:

ValueNode this.expression

setName

public void setName(String name)

Set the name in this ResultColumn. This is useful when you don't know the name at the time you create the ResultColumn, for example, in an insert-select statement, where you want the names of the result columns to match the table being inserted into, not the table they came from.

Parameters:

name - The name to set in this ResultColumn

isNameGenerated

public boolean isNameGenerated()

Is the name for this ResultColumn generated?

setNameGenerated

public void setNameGenerated(boolean value)

Set that this result column name is generated.

adjustVirtualColumnId

public void adjustVirtualColumnId(int adjust)

Adjust the virtualColumnId for this ResultColumn by the specified amount

Parameters:

adjust - The adjustment for the virtualColumnId

setVirtualColumnId

public void setVirtualColumnId(int id)

Set the virtualColumnId for this ResultColumn

Parameters:

id - The virtualColumnId for this ResultColumn

getVirtualColumnId

public int getVirtualColumnId()

Get the virtualColumnId for this ResultColumn

Returns:

virtualColumnId for this ResultColumn

toString

public 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

Returns:

This object as a String

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

Parameters:

depth - The depth of this node in the tree

getTableNameObject

public TableName getTableNameObject()

getReference

public ColumnReference getReference()

isEquivalent

public boolean isEquivalent(ValueNode o)
                     throws StandardException

Description copied from class: ValueNode

Tests if this node is equivalent to the specified ValueNode. Two ValueNodes are considered equivalent if they will evaluate to the same value during query execution.

This method provides basic expression matching facility for the derived class of ValueNode and it is used by the language layer to compare the node structural form of the two expressions for equivalence at bind phase.

Note that it is not comparing the actual row values at runtime to produce a result; hence, when comparing SQL NULLs, they are considered to be equivalent and not unknown.

One usage case of this method in this context is to compare the select column expression against the group by expression to check if they are equivalent. e.g.:

SELECT c1+c2 FROM t1 GROUP BY c1+c2

In general, node equivalence is determined by the derived class of ValueNode. But they generally abide to the rules below:

• The two ValueNodes must be of the same node type to be considered equivalent. e.g.: CastNode vs. CastNode - equivalent (if their args also match), ColumnReference vs CastNode - not equivalent.
• If node P contains other ValueNode(s) and so on, those node(s) must also be of the same node type to be considered equivalent.
• If node P takes a parameter list, then the number of arguments and its arguments for the two nodes must also match to be considered equivalent. e.g.: CAST(c1 as INTEGER) vs CAST(c1 as SMALLINT), they are not equivalent.
• When comparing SQL NULLs in this context, they are considered to be equivalent.
• If this does not apply or it is determined that the two nodes are not equivalent then the derived class of this method should return false; otherwise, return true.

Specified by:

isEquivalent in class ValueNode

Parameters:

o - the node to compare this ValueNode against.

Returns:

true if the two nodes are equivalent, false otherwise.

Throws:

StandardException