| 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 | * View.java |
| 29 | * --------------- |
| 30 | * Author: Volker Berlin |
| 31 | * |
| 32 | * Created on 31.05.2004 |
| 33 | */ |
| 34 | package smallsql.database; |
| 35 | |
| 36 | import java.io.*; |
| 37 | |
| 38 | |
| 39 | /** |
| 40 | * @author Volker Berlin |
| 41 | */ |
| 42 | class View extends TableView{ |
| 43 | final String sql; |
| 44 | final CommandSelect commandSelect; |
| 45 | |
| 46 | |
| 47 | /** |
| 48 | * Constructor for loading an existing view. |
| 49 | */ |
| 50 | View(SSConnection con, String name, RandomAccessFile raFile, long offset) throws Exception{ |
| 51 | super( name, new Columns() ); |
| 52 | StorePage storePage = new StorePage( null, -1, raFile, offset); |
| 53 | StoreImpl store = StoreImpl.createStore( null, storePage, SQLTokenizer.SELECT, offset); |
| 54 | sql = store.readString(); |
| 55 | |
| 56 | // read additional informations |
| 57 | int type; |
| 58 | while((type = store.readInt()) != 0){ |
| 59 | int offsetInPage = store.getCurrentOffsetInPage(); |
| 60 | int size = store.readInt(); |
| 61 | switch(type){ |
| 62 | |
| 63 | } |
| 64 | store.setCurrentOffsetInPage(offsetInPage + size); |
| 65 | } |
| 66 | |
| 67 | raFile.close(); |
| 68 | commandSelect = (CommandSelect)new SQLParser().parse(con, sql); |
| 69 | createColumns(con); |
| 70 | } |
| 71 | |
| 72 | |
| 73 | /** |
| 74 | * Constructor for a new view. Is call on execute() of CREATE VIEW. This view is not init. |
| 75 | */ |
| 76 | View(Database database, String name, String sql) throws Exception{ |
| 77 | super( name, new Columns() ); |
| 78 | this.sql = sql; |
| 79 | this.commandSelect = null; |
| 80 | write(database); |
| 81 | } |
| 82 | |
| 83 | |
| 84 | /** |
| 85 | * Constructor for a UNION |
| 86 | */ |
| 87 | View(SSConnection con, CommandSelect commandSelect) throws Exception{ |
| 88 | super("UNION", new Columns()); |
| 89 | this.sql = null; |
| 90 | this.commandSelect = commandSelect; |
| 91 | createColumns(con); |
| 92 | } |
| 93 | |
| 94 | |
| 95 | private void createColumns(SSConnection con) throws Exception{ |
| 96 | commandSelect.compile(con); |
| 97 | Expressions exprs = commandSelect.columnExpressions; |
| 98 | for(int c=0; c<exprs.size(); c++){ |
| 99 | Expression expr = exprs.get(c); |
| 100 | if(expr instanceof ExpressionName){ |
| 101 | Column column = ((ExpressionName)expr).getColumn().copy(); |
| 102 | column.setName( expr.getAlias() ); |
| 103 | columns.add( column ); |
| 104 | }else{ |
| 105 | columns.add( new ColumnExpression(expr)); |
| 106 | } |
| 107 | } |
| 108 | } |
| 109 | |
| 110 | |
| 111 | /** |
| 112 | * Drop the View. This method is static that the file does not need to load and also corrupt files can be dropped. |
| 113 | */ |
| 114 | static void drop(Database database, String name) throws Exception{ |
| 115 | File file = new File( Utils.createTableViewFileName( database, name ) ); |
| 116 | boolean ok = file.delete(); |
| 117 | if(!ok) throw Utils.createSQLException("View '" + name + "' can't drop."); |
| 118 | } |
| 119 | |
| 120 | |
| 121 | private void write(Database database) throws Exception{ |
| 122 | RandomAccessFile raFile = createFile( database ); |
| 123 | StorePage storePage = new StorePage( null, -1, raFile, 8); |
| 124 | StoreImpl store = StoreImpl.createStore( null, storePage, SQLTokenizer.CREATE, 8); |
| 125 | store.writeString(sql); |
| 126 | |
| 127 | // write additional informations |
| 128 | store.writeInt( 0 ); // no more additinal informations |
| 129 | |
| 130 | store.writeFinsh(null); |
| 131 | raFile.close(); |
| 132 | } |
| 133 | |
| 134 | void writeMagic(RandomAccessFile raFile) throws Exception{ |
| 135 | raFile.writeInt(MAGIC_VIEW); |
| 136 | raFile.writeInt(TABLE_VIEW_VERSION); |
| 137 | } |
| 138 | |
| 139 | } |