001: /*
002: * $Id: TruncateCommand.java,v 1.7 2005/12/20 18:32:28 ahimanikya Exp $
003: * =======================================================================
004: * Copyright (c) 2004 Axion Development Team. All rights reserved.
005: *
006: * Redistribution and use in source and binary forms, with or without
007: * modification, are permitted provided that the following conditions
008: * are met:
009: *
010: * 1. Redistributions of source code must retain the above
011: * copyright notice, this list of conditions and the following
012: * disclaimer.
013: *
014: * 2. Redistributions in binary form must reproduce the above copyright
015: * notice, this list of conditions and the following disclaimer in
016: * the documentation and/or other materials provided with the
017: * distribution.
018: *
019: * 3. The names "Tigris", "Axion", nor the names of its contributors may
020: * not be used to endorse or promote products derived from this
021: * software without specific prior written permission.
022: *
023: * 4. Products derived from this software may not be called "Axion", nor
024: * may "Tigris" or "Axion" appear in their names without specific prior
025: * written permission.
026: *
027: * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
028: * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
029: * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
030: * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
031: * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
032: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
033: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
034: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
035: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
036: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
037: * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
038: * =======================================================================
039: */
040:
041: package org.axiondb.engine.commands;
042:
043: import java.util.Iterator;
044:
045: import org.axiondb.AxionException;
046: import org.axiondb.Database;
047: import org.axiondb.Table;
048: import org.axiondb.constraints.ForeignKeyConstraint;
049: import org.axiondb.engine.tables.TableView;
050: import org.axiondb.jdbc.AxionResultSet;
051:
052: /**
053: * A <code>TRUNCATE TABLE</code> command.
054: *
055: * @version $Revision: 1.7 $ $Date: 2005/12/20 18:32:28 $
056: * @author Ahimanikya Satapathy
057: */
058: public class TruncateCommand extends BaseAxionCommand {
059:
060: public TruncateCommand() {
061: }
062:
063: public int executeUpdate(org.axiondb.Database db)
064: throws AxionException {
065: assertNotReadOnly(db);
066: Table t = db.getTable(_tableName);
067:
068: if (t != null && !t.getType().equals(TableView.VIEW)
069: && !t.getType().equals(Table.SYSTEM_TABLE_TYPE)) {
070: checkConstraint(db, t);
071: int rowcount = t.getRowCount();
072: t.truncate();
073: setEffectedRowCount(rowcount);
074: return rowcount;
075: } else {
076: throw new AxionException("Table " + _tableName
077: + " not found.");
078: }
079: }
080:
081: /** Unsupported */
082: public AxionResultSet executeQuery(Database database)
083: throws AxionException {
084: throw new UnsupportedOperationException("Use executeUpdate.");
085: }
086:
087: public boolean execute(Database db) throws AxionException {
088: executeUpdate(db);
089: return false;
090: }
091:
092: public void setObjectName(String theTableName) {
093: _tableName = theTableName;
094: }
095:
096: protected void checkConstraint(Database db, Table table)
097: throws AxionException {
098: for (Iterator iter = table.getConstraints(); iter.hasNext();) {
099: Object constraint = iter.next();
100: if (constraint instanceof ForeignKeyConstraint) {
101: ForeignKeyConstraint fk = (ForeignKeyConstraint) constraint;
102: if (fk.getParentTableName().equals(
103: fk.getChildTableName())) {
104: // do nothing
105: } else if (table.getName().equals(
106: fk.getParentTableName())) {
107: Table childTable = db.getTable(fk
108: .getChildTableName());
109: // someone else refering this table and has rows count > 0
110: if (childTable.getRowCount() != 0) {
111: throw new AxionException(
112: "Child table exist, can't truncate");
113: }
114: }
115: }
116: }
117: }
118:
119: private String _tableName;
120: }
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