org.eigenbase.sql.validate
Class SelectScope

java.lang.Object
  org.eigenbase.sql.validate.DelegatingScope
      org.eigenbase.sql.validate.ListScope
          org.eigenbase.sql.validate.SelectScope

All Implemented Interfaces:

SqlValidatorScope

public class SelectScope
extends ListScope

The name-resolution scope of a SELECT clause. The objects visible are those in the FROM clause, and objects inherited from the parent scope.

This object is both a SqlValidatorScope and a SqlValidatorNamespace. In the query

SELECT name FROM (
     SELECT *
     FROM emp
     WHERE gender = 'F')

we need to use the SelectScope as a SqlValidatorNamespace when resolving 'name', and as a SqlValidatorScope when resolving 'gender'.

Scopes

In the query

 SELECT expr1
 FROM t1,
     t2,
     (SELECT expr2 FROM t3) AS q3
 WHERE c1 IN (SELECT expr3 FROM t4)
 ORDER BY expr4

The scopes available at various points of the query are as follows:

• expr1 can see t1, t2, q3
• expr2 can see t3
• expr3 can see t4, t1, t2
• expr4 can see t1, t2, q3, plus (depending upon the dialect) any aliases defined in the SELECT clause

Namespaces

In the above query, there are 4 namespaces:

• t1
• t2
• (SELECT expr2 FROM t3) AS q3
• (SELECT expr3 FROM t4)

Since:

Mar 25, 2003

Version:

$Id: //open/dev/farrago/src/org/eigenbase/sql/validate/SelectScope.java#17 $

Author:

jhyde

See Also:

SelectNamespace

Field Summary

private List<SqlNode>	expandedSelectList
private SqlNodeList	orderList List of column names which sort this scope.
private SqlSelect	select
protected List<String>	windowNames
private SqlValidatorScope	windowParent Scope to use to resolve windows

Fields inherited from class org.eigenbase.sql.validate.ListScope

children, childrenNames

Fields inherited from class org.eigenbase.sql.validate.DelegatingScope

parent, validator

Constructor Summary

SelectScope(SqlValidatorScope parent, SqlValidatorScope winParent, SqlSelect select)
Creates a scope corresponding to a SELECT clause.

Method Summary

void	addWindowName(String winName)
boolean	existingWindowName(String winName)
List<SqlNode>	getExpandedSelectList()
SqlMonotonicity	getMonotonicity(SqlNode expr) Returns whether an expression is monotonic in this scope.
SqlSelect	getNode() Returns the root node of this scope.
SqlNodeList	getOrderList() Returns the expressions by which the rows in this scope are sorted.
SqlValidatorTable	getTable()
SqlWindow	lookupWindow(String name) Finds a window with a given name.
void	setExpandedSelectList(List<SqlNode> selectList)

Methods inherited from class org.eigenbase.sql.validate.ListScope

addChild, findAliases, findAllColumnNames, findQualifyingTableName, getChild, getChildren, resolve, resolveColumn

Methods inherited from class org.eigenbase.sql.validate.DelegatingScope

addColumnNames, fullyQualify, getOperandScope, getParent, getValidator, validateExpr

Methods inherited from class java.lang.Object

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

Field Detail

select

private final SqlSelect select

windowNames

protected final List<String> windowNames

expandedSelectList

private List<SqlNode> expandedSelectList

orderList

private SqlNodeList orderList

List of column names which sort this scope. Empty if this scope is not sorted. Null if has not been computed yet.

windowParent

private final SqlValidatorScope windowParent

Scope to use to resolve windows

Constructor Detail

SelectScope

SelectScope(SqlValidatorScope parent,
            SqlValidatorScope winParent,
            SqlSelect select)

Creates a scope corresponding to a SELECT clause.

Parameters:

parent - Parent scope, must not be null

winParent - Scope for window parent, may be null

select - Select clause

Method Detail

getTable

public SqlValidatorTable getTable()

getNode

public SqlSelect getNode()

Description copied from interface: SqlValidatorScope

Returns the root node of this scope.

lookupWindow

public SqlWindow lookupWindow(String name)

Description copied from interface: SqlValidatorScope

Finds a window with a given name. Returns null if not found.

Specified by:

lookupWindow in interface SqlValidatorScope

Overrides:

lookupWindow in class DelegatingScope

getMonotonicity

public SqlMonotonicity getMonotonicity(SqlNode expr)

Description copied from interface: SqlValidatorScope

Returns whether an expression is monotonic in this scope. For example, if the scope has previously been sorted by columns X, Y, then X is monotonic in this scope, but Y is not.

Specified by:

getMonotonicity in interface SqlValidatorScope

Overrides:

getMonotonicity in class DelegatingScope

getOrderList

public SqlNodeList getOrderList()

Description copied from interface: SqlValidatorScope

Returns the expressions by which the rows in this scope are sorted. If the rows are unsorted, returns null.

Specified by:

getOrderList in interface SqlValidatorScope

Overrides:

getOrderList in class DelegatingScope

addWindowName

public void addWindowName(String winName)

existingWindowName

public boolean existingWindowName(String winName)

getExpandedSelectList

public List<SqlNode> getExpandedSelectList()

setExpandedSelectList

public void setExpandedSelectList(List<SqlNode> selectList)