org.eigenbase.sql.validate
Class AggregatingSelectScope

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

All Implemented Interfaces:

AggregatingScope, SqlValidatorScope

public class AggregatingSelectScope
extends DelegatingScope
implements AggregatingScope

Scope for resolving identifers within a SELECT statement which has a GROUP BY clause.

The same set of identifiers are in scope, but it won't allow access to identifiers or expressions which are not group-expressions.

Since:

Mar 25, 2003

Version:

$Id: //open/dev/farrago/src/org/eigenbase/sql/validate/AggregatingSelectScope.java#11 $

Author:

jhyde

Field Summary

private boolean	distinct
private List<SqlNode>	groupExprList
private SqlSelect	select

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

parent, validator

Constructor Summary

AggregatingSelectScope(SqlValidatorScope selectScope, SqlSelect select, boolean distinct)

Method Summary

boolean	checkAggregateExpr(SqlNode expr, boolean deep) Checks whether an expression is constant within the GROUP BY clause.
private List<SqlNode>	getGroupExprs() Returns the expressions that are in the GROUP BY clause (or the SELECT DISTINCT clause, if distinct) and that can therefore be referenced without being wrapped in aggregate functions.
SqlNode	getNode() Returns the root node of this scope.
SqlValidatorScope	getOperandScope(SqlCall call) Returns the scope within which operands to a call are to be validated.
void	validateExpr(SqlNode expr) Performs any scope-specific validation of an expression.

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

addChild, addColumnNames, findAliases, findAllColumnNames, findQualifyingTableName, fullyQualify, getMonotonicity, getOrderList, getParent, getValidator, lookupWindow, resolve, resolveColumn

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.eigenbase.sql.validate.SqlValidatorScope

addChild, findAliases, findAllColumnNames, findQualifyingTableName, fullyQualify, getMonotonicity, getOrderList, getValidator, lookupWindow, resolve, resolveColumn

Field Detail

select

private final SqlSelect select

distinct

private final boolean distinct

groupExprList

private final List<SqlNode> groupExprList

Constructor Detail

AggregatingSelectScope

AggregatingSelectScope(SqlValidatorScope selectScope,
                       SqlSelect select,
                       boolean distinct)

Method Detail

getGroupExprs

private List<SqlNode> getGroupExprs()

Returns the expressions that are in the GROUP BY clause (or the SELECT DISTINCT clause, if distinct) and that can therefore be referenced without being wrapped in aggregate functions.

The expressions are fully-qualified, and any "*" in select clauses are expanded.

Returns:

list of grouping expressions

getNode

public SqlNode getNode()

Description copied from interface: SqlValidatorScope

Returns the root node of this scope.

Specified by:

getNode in interface SqlValidatorScope

getOperandScope

public SqlValidatorScope getOperandScope(SqlCall call)

Description copied from interface: SqlValidatorScope

Returns the scope within which operands to a call are to be validated. Usually it is this scope, but when the call is to an aggregate function and this is an aggregating scope, it will be a a different scope.

Specified by:

getOperandScope in interface SqlValidatorScope

Overrides:

getOperandScope in class DelegatingScope

Parameters:

call - Call

Returns:

Scope within which to validate arguments to call.

checkAggregateExpr

public boolean checkAggregateExpr(SqlNode expr,
                                  boolean deep)

Description copied from interface: AggregatingScope

Checks whether an expression is constant within the GROUP BY clause. If the expression completely matches an expression in the GROUP BY clause, returns true. If the expression is constant within the group, but does not exactly match, returns false. If the expression is not constant, throws an exception. Examples:

• If we are 'f(b, c)' in 'SELECT a + f(b, c) FROM t GROUP BY a', then the whole expression matches a group column. Return true.
• Just an ordinary expression in a GROUP BY query, such as 'f(SUM(a), 1, b)' in 'SELECT f(SUM(a), 1, b) FROM t GROUP BY b'. Returns false.
• Illegal expression, such as 'f(5, a, b)' in 'SELECT f(a, b) FROM t GROUP BY a'. Throws when it enounters the 'b' operand, because it is not in the group clause.

Specified by:

checkAggregateExpr in interface AggregatingScope

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