| 1 | /* ============================================================= |
| 2 | * SmallSQL : a free Java DBMS library for the Java(tm) platform |
| 3 | * ============================================================= |
| 4 | * |
| 5 | * (C) Copyright 2004-2006, by Volker Berlin. |
| 6 | * |
| 7 | * Project Info: http://www.smallsql.de/ |
| 8 | * |
| 9 | * This library is free software; you can redistribute it and/or modify it |
| 10 | * under the terms of the GNU Lesser General Public License as published by |
| 11 | * the Free Software Foundation; either version 2.1 of the License, or |
| 12 | * (at your option) any later version. |
| 13 | * |
| 14 | * This library is distributed in the hope that it will be useful, but |
| 15 | * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
| 16 | * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public |
| 17 | * License for more details. |
| 18 | * |
| 19 | * You should have received a copy of the GNU Lesser General Public |
| 20 | * License along with this library; if not, write to the Free Software |
| 21 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, |
| 22 | * USA. |
| 23 | * |
| 24 | * [Java is a trademark or registered trademark of Sun Microsystems, Inc. |
| 25 | * in the United States and other countries.] |
| 26 | * |
| 27 | * --------------- |
| 28 | * ExpressionFunctionRand.java |
| 29 | * --------------- |
| 30 | * Author: Volker Berlin |
| 31 | * |
| 32 | */ |
| 33 | package smallsql.database; |
| 34 | |
| 35 | import java.util.Random; |
| 36 | |
| 37 | |
| 38 | final class ExpressionFunctionRand extends ExpressionFunctionReturnFloat { |
| 39 | |
| 40 | final static private Random random = new Random(); |
| 41 | |
| 42 | |
| 43 | final int getFunction(){ return SQLTokenizer.RAND; } |
| 44 | |
| 45 | |
| 46 | boolean isNull() throws Exception{ |
| 47 | return getParams().length == 1 && param1.isNull(); |
| 48 | } |
| 49 | |
| 50 | |
| 51 | final double getDouble() throws Exception{ |
| 52 | if(getParams().length == 0) |
| 53 | return random.nextDouble(); |
| 54 | if(isNull()) return 0; |
| 55 | return new Random(param1.getLong()).nextDouble(); |
| 56 | } |
| 57 | } |