/*
* Copyright 2004-2013 H2 Group. Multiple-Licensed under the H2 License,
* Version 1.0, and under the Eclipse Public License, Version 1.0
* (http://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.lealone.expression;
import org.lealone.command.dml.Query;
import org.lealone.dbobject.table.ColumnResolver;
import org.lealone.dbobject.table.TableFilter;
import org.lealone.engine.Session;
import org.lealone.result.ResultInterface;
import org.lealone.util.StringUtils;
import org.lealone.value.Value;
import org.lealone.value.ValueBoolean;
/**
* An 'exists' condition as in WHERE EXISTS(SELECT ...)
*/
public class ConditionExists extends Condition {
private final Query query;
public ConditionExists(Query query) {
this.query = query;
}
public Value getValue(Session session) {
query.setSession(session);
ResultInterface result = session.createSubqueryResult(query, 1); //query.query(1);
session.addTemporaryResult(result);
boolean r = result.getRowCount() > 0;
return ValueBoolean.get(r);
}
public Expression optimize(Session session) {
query.prepare();
return this;
}
public String getSQL(boolean isDistributed) {
return "EXISTS(\n" + StringUtils.indent(query.getPlanSQL(), 4, false) + ")";
}
public void updateAggregate(Session session) {
// TODO exists: is it allowed that the subquery contains aggregates?
// probably not
// select id from test group by id having exists (select * from test2
// where id=count(test.id))
}
public void mapColumns(ColumnResolver resolver, int level) {
query.mapColumns(resolver, level + 1);
}
public void setEvaluatable(TableFilter tableFilter, boolean b) {
query.setEvaluatable(tableFilter, b);
}
public boolean isEverything(ExpressionVisitor visitor) {
return query.isEverything(visitor);
}
public int getCost() {
return query.getCostAsExpression();
}
}