org.eigenbase.sql2rel
Interface SubqueryConverter

All Known Implementing Classes:

ScalarSubqueryConverter, SqlToRelConverter.NoOpSubqueryConverter

public interface SubqueryConverter

SubqueryConverter provides the interface for classes that convert subqueries into equivalent expressions.

Version:

$Id: //open/dev/farrago/src/org/eigenbase/sql2rel/SubqueryConverter.java#4 $

Author:

Zelaine Fong

Method Summary

boolean	canConvertSubquery()
RexNode	convertSubquery(SqlCall subquery, SqlToRelConverter parentConverter, boolean isExists, boolean isExplain) Converts the subquery to an equivalent expression.

Method Detail

canConvertSubquery

boolean canConvertSubquery()

Returns:

true if the subquery can be converted

convertSubquery

RexNode convertSubquery(SqlCall subquery,
                        SqlToRelConverter parentConverter,
                        boolean isExists,
                        boolean isExplain)

Converts the subquery to an equivalent expression.

Parameters:

subquery - the SqlNode tree corresponding to a subquery

parentConverter - sqlToRelConverter of the parent query

isExists - whether the subquery is part of an EXISTS expression

isExplain - whether the subquery is part of an EXPLAIN PLAN statement

Returns:

the equivalent expression or null if the subquery couldn't be converted