org.eigenbase.sql.validate
Class OrderByScope

java.lang.Object
  org.eigenbase.sql.validate.DelegatingScope
      org.eigenbase.sql.validate.OrderByScope

All Implemented Interfaces:

SqlValidatorScope

public class OrderByScope
extends DelegatingScope

Represents the name-resolution context for expressions in an ORDER BY clause.

In some dialects of SQL, the ORDER BY clause can reference column aliases in the SELECT clause. For example, the query

SELECT empno AS x
FROM emp
ORDER BY x

is valid.

Since:

Mar 25, 2003

Version:

$Id: //open/dev/farrago/src/org/eigenbase/sql/validate/OrderByScope.java#10 $

Author:

jhyde

Field Summary

private SqlNodeList	orderList
private SqlSelect	select

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

parent, validator

Constructor Summary

OrderByScope(SqlValidatorScope parent, SqlNodeList orderList, SqlSelect select)

Method Summary

void	findAllColumnNames(List<SqlMoniker> result) Collects the SqlMonikers of all possible columns in this scope.
SqlIdentifier	fullyQualify(SqlIdentifier identifier) Converts an identifier into a fully-qualified identifier.
SqlNode	getNode() Returns the root node of this scope.
RelDataType	resolveColumn(String name, SqlNode ctx) Resolves a single identifier to a column, and returns the datatype of that column.
void	validateExpr(SqlNode expr) Performs any scope-specific validation of an expression.

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

addChild, addColumnNames, findAliases, findQualifyingTableName, getMonotonicity, getOperandScope, getOrderList, getParent, getValidator, lookupWindow, resolve

Methods inherited from class java.lang.Object

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

Field Detail

orderList

private final SqlNodeList orderList

select

private final SqlSelect select

Constructor Detail

OrderByScope

OrderByScope(SqlValidatorScope parent,
             SqlNodeList orderList,
             SqlSelect select)

Method Detail

getNode

public SqlNode getNode()

Description copied from interface: SqlValidatorScope

Returns the root node of this scope.

findAllColumnNames

public void findAllColumnNames(List<SqlMoniker> result)

Description copied from interface: SqlValidatorScope

Collects the SqlMonikers of all possible columns in this scope.

Specified by:

findAllColumnNames in interface SqlValidatorScope

Overrides:

findAllColumnNames in class DelegatingScope

Parameters:

result - an array list of strings to add the result to

fullyQualify

public SqlIdentifier fullyQualify(SqlIdentifier identifier)

Description copied from class: DelegatingScope

Converts an identifier into a fully-qualified identifier. For example, the "empno" in "select empno from emp natural join dept" becomes "emp.empno".

If the identifier cannot be resolved, throws. Never returns null.

Specified by:

fullyQualify in interface SqlValidatorScope

Overrides:

fullyQualify in class DelegatingScope

resolveColumn

public RelDataType resolveColumn(String name,
                                 SqlNode ctx)

Description copied from interface: SqlValidatorScope

Resolves a single identifier to a column, and returns the datatype of that column.

If it cannot find the column, returns null. If the column is ambiguous, throws an error with context ctx.

Specified by:

resolveColumn in interface SqlValidatorScope

Overrides:

resolveColumn in class DelegatingScope

Parameters:

name - Name of column

ctx - Context for exception

Returns:

Type of column, if found and unambiguous; null if not found

validateExpr

public void validateExpr(SqlNode expr)

Description copied from interface: SqlValidatorScope

Performs any scope-specific validation of an expression. For example, an aggregating scope requires that expressions are valid aggregations. The expression has already been validated.

Specified by:

validateExpr in interface SqlValidatorScope

Overrides:

validateExpr in class DelegatingScope