/*
* Copyright 2004-2023 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (https://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.table;
import org.h2.engine.Database;
import org.h2.engine.SessionLocal;
import org.h2.index.DualIndex;
import org.h2.index.Index;
/**
* The DUAL table for selects without a FROM clause.
*/
public class DualTable extends VirtualTable {
/**
* The name of the range table.
*/
public static final String NAME = "DUAL";
/**
* Create a new range with the given start and end expressions.
*
* @param database
* the database
*/
public DualTable(Database database) {
super(database.getMainSchema(), 0, NAME);
setColumns(new Column[0]);
}
@Override
public StringBuilder getSQL(StringBuilder builder, int sqlFlags) {
return builder.append(NAME);
}
@Override
public boolean canGetRowCount(SessionLocal session) {
return true;
}
@Override
public long getRowCount(SessionLocal session) {
return 1L;
}
@Override
public TableType getTableType() {
return TableType.SYSTEM_TABLE;
}
@Override
public Index getScanIndex(SessionLocal session) {
return new DualIndex(this);
}
@Override
public long getMaxDataModificationId() {
return 0L;
}
@Override
public long getRowCountApproximation(SessionLocal session) {
return 1L;
}
@Override
public boolean isDeterministic() {
return true;
}
}