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*
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* please contact info@exolab.org.
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* 5. Due credit should be given to the Exolab Project
* (http://www.exolab.org/).
*
* THIS SOFTWARE IS PROVIDED BY INTALIO, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
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* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Copyright 1999 (C) Intalio, Inc. All Rights Reserved.
*
* $Id$
*/
package org.castor.cpa.persistence.sql.driver;
import java.util.Enumeration;
import java.util.Vector;
import org.exolab.castor.jdo.engine.JDBCSyntax;
import org.exolab.castor.persist.spi.PersistenceFactory;
/**
* QueryExpression for SAP DB.
*
* @author <a href="mailto:on@ibis.odessa.ua">Oleg Nitz</a>
* @version $Revision$ $Date: 2004-10-01 07:25:46 -0600 (Fri, 01 Oct 2004) $
*/
public final class SapDbQueryExpression extends JDBCQueryExpression {
public SapDbQueryExpression(final PersistenceFactory factory) {
super(factory);
}
public String getStatement(final boolean lock) {
Join join;
StringBuffer sql;
boolean first;
int size;
Vector<String> sorted = new Vector<String>();
sql = new StringBuffer();
sql.append(JDBCSyntax.SELECT);
if (_distinct) {
sql.append(JDBCSyntax.DISTINCT);
}
sql.append(getColumnList());
sql.append(JDBCSyntax.FROM);
// Add all the tables to the FROM clause
// They should go in the special order: the table from the left side of outer join
// should go before the table from the right side.
// first add elements that participate in outer joins
Enumeration<Join> joinEnumeration = _joins.elements();
while (joinEnumeration.hasMoreElements()) {
int left;
int right;
join = joinEnumeration.nextElement();
if (!join._outer) {
continue;
}
left = sorted.indexOf(join._leftTable);
right = sorted.indexOf(join._rightTable);
if (left >= 0 && right >= 0) {
if (left > right) {
sorted.removeElement(join._leftTable);
sorted.insertElementAt(join._leftTable, right);
}
} else if ((left < 0) && (right >= 0)) {
sorted.insertElementAt(join._leftTable, right);
} else if ((left >= 0) && (right < 0)) {
sorted.insertElementAt(join._rightTable, left + 1);
} else { // (left < 0 && right < 0)
sorted.addElement(join._leftTable);
sorted.addElement(join._rightTable);
}
}
// now add elements that don't participate in outer joins
Enumeration<String> tableEnumeration = _tables.keys();
while (tableEnumeration.hasMoreElements()) {
String name = tableEnumeration.nextElement();
if (!sorted.contains(name)) {
sorted.addElement(name);
}
}
// Append all the tables (from sorted) to the sql string.
Enumeration<String> sortedEnumeration = sorted.elements();
while (sortedEnumeration.hasMoreElements()) {
String tableAlias = sortedEnumeration.nextElement();
String tableName = _tables.get(tableAlias);
if (tableAlias.equals(tableName)) {
sql.append(_factory.quoteName(tableName));
} else {
sql.append(_factory.quoteName(tableName) + " "
+ _factory.quoteName(tableAlias));
}
if (sortedEnumeration.hasMoreElements()) {
sql.append(JDBCSyntax.TABLE_SEPARATOR);
}
}
first = true;
// Use asterisk notation to denote a left outer join
// and equals to denote an inner join
size = _joins.size();
for (int i = 0; i < size; ++i) {
if (first) {
sql.append(JDBCSyntax.WHERE);
first = false;
} else {
sql.append(JDBCSyntax.AND);
}
join = _joins.elementAt(i);
for (int j = 0; j < join._leftColumns.length; ++j) {
if (j > 0) {
sql.append(JDBCSyntax.AND);
}
sql.append(_factory.quoteName(join._leftTable
+ JDBCSyntax.TABLE_COLUMN_SEPARATOR
+ join._leftColumns[j]));
sql.append(OP_EQUALS);
sql.append(_factory.quoteName(join._rightTable
+ JDBCSyntax.TABLE_COLUMN_SEPARATOR
+ join._rightColumns[j]));
if (join._outer) {
sql.append("(+)");
}
}
}
first = addWhereClause(sql, first);
if (_order != null) {
sql.append(JDBCSyntax.ORDER_BY).append(_order);
}
if (_limit != null) {
if (_distinct) {
sql.insert(0, "SELECT * FROM (");
sql.append(")");
}
sql.append(JDBCSyntax.LIMIT);
if (_offset != null) {
sql.append(_offset).append(", ");
}
sql.append(_limit);
}
// Use WITH LOCK to lock selected tables.
if (lock) {
sql.append(" WITH LOCK");
}
return sql.toString();
}
/**
* Indicates that SapDB supports an OQL LIMIT clause.
*
* @return true to indicate that SapDB supports an OQL LIMIT clause.
*/
public boolean isLimitClauseSupported() {
return true;
}
/**
* Indicates that SapDB supports an OQL OFFSET clause for versions >= 7.6.0.
*
* @return true to indicate that SapDB supports an OQL OFFSET clause.
*/
public boolean isOffsetClauseSupported() {
return true;
}
}