package org.apache.torque.adapter;
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Statement;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashSet;
import java.util.ListIterator;
import java.util.Set;
import org.apache.torque.util.Query;
import org.apache.torque.util.UniqueList;
/**
* This code should be used for an Oracle database pool.
*
* @author <a href="mailto:jon@clearink.com">Jon S. Stevens</a>
* @author <a href="mailto:bmclaugh@algx.net">Brett McLaughlin</a>
* @author <a href="mailto:bschneider@vecna.com">Bill Schneider</a>
* @author <a href="mailto:dlr@finemaltcoding.com">Daniel Rall</a>
* @version $Id: DBOracle.java 476550 2006-11-18 16:08:37Z tfischer $
*/
public class DBOracle extends AbstractDBAdapter
{
/**
* Serial version
*/
private static final long serialVersionUID = 8966976210230241194L;
/** date format used in getDateString() */
private static final String DATE_FORMAT = "dd-MM-yyyy HH:mm:ss";
/**
* Empty constructor.
*/
protected DBOracle()
{
}
/**
* This method is used to ignore case.
*
* @param in The string to transform to upper case.
* @return The upper case string.
*/
public String toUpperCase(String in)
{
return new StringBuffer("UPPER(").append(in).append(")").toString();
}
/**
* This method is used to ignore case.
*
* @param in The string whose case to ignore.
* @return The string in a case that can be ignored.
*/
public String ignoreCase(String in)
{
return new StringBuffer("UPPER(").append(in).append(")").toString();
}
/**
* This method is used to format any date string.
*
* @param date the Date to format
* @return The date formatted String for Oracle.
*/
public String getDateString(Date date)
{
return "TO_DATE('" + new SimpleDateFormat(DATE_FORMAT).format(date)
+ "', 'DD-MM-YYYY HH24:MI:SS')";
}
/**
* @see org.apache.torque.adapter.DB#getIDMethodType()
*/
public String getIDMethodType()
{
return SEQUENCE;
}
/**
* Returns the next key from a sequence. Uses the following
* implementation:
*
* <blockquote><code><pre>
* select sequenceName.nextval from dual
* </pre></code></blockquote>
*
* @param sequenceName The name of the sequence (should be of type
* <code>String</code>).
* @return SQL to retreive the next database key.
* @see org.apache.torque.adapter.DB#getIDMethodSQL(Object)
*/
public String getIDMethodSQL(Object sequenceName)
{
return ("select " + sequenceName + ".nextval from dual");
}
/**
* Locks the specified table.
*
* @param con The JDBC connection to use.
* @param table The name of the table to lock.
* @exception SQLException No Statement could be created or executed.
*/
public void lockTable(Connection con, String table) throws SQLException
{
Statement statement = con.createStatement();
StringBuffer stmt = new StringBuffer();
stmt.append("SELECT next_id FROM ")
.append(table)
.append(" FOR UPDATE");
statement.executeQuery(stmt.toString());
}
/**
* Unlocks the specified table.
*
* @param con The JDBC connection to use.
* @param table The name of the table to unlock.
* @exception SQLException No Statement could be created or executed.
*/
public void unlockTable(Connection con, String table) throws SQLException
{
// Tables in Oracle are unlocked when a commit is issued. The
// user may have issued a commit but do it here to be sure.
con.commit();
}
/**
* This method is used to check whether the database supports
* limiting the size of the resultset.
*
* @return LIMIT_STYLE_ORACLE.
* @deprecated This should not be exposed to the outside
*/
public int getLimitStyle()
{
return DB.LIMIT_STYLE_ORACLE;
}
/**
* Return true for Oracle
* @see org.apache.torque.adapter.AbstractDBAdapter#supportsNativeLimit()
*/
public boolean supportsNativeLimit()
{
return true;
}
/**
* Return true for Oracle
* @see org.apache.torque.adapter.AbstractDBAdapter#supportsNativeOffset()
*/
public boolean supportsNativeOffset()
{
return true;
}
/**
* Build Oracle-style query with limit or offset.
* If the original SQL is in variable: query then the requlting
* SQL looks like this:
* <pre>
* SELECT B.* FROM (
* SELECT A.*, rownum as TORQUE$ROWNUM FROM (
* query
* ) A
* ) B WHERE B.TORQUE$ROWNUM > offset AND B.TORQUE$ROWNUM
* <= offset + limit
* </pre>
*
* @param query The query to modify
* @param offset the offset Value
* @param limit the limit Value
*/
public void generateLimits(Query query, int offset, int limit)
{
StringBuffer preLimit = new StringBuffer()
.append("SELECT B.* FROM ( ")
.append("SELECT A.*, rownum AS TORQUE$ROWNUM FROM ( ");
StringBuffer postLimit = new StringBuffer()
.append(" ) A ")
.append(" ) B WHERE ");
if (offset > 0)
{
postLimit.append(" B.TORQUE$ROWNUM > ")
.append(offset);
if (limit >= 0)
{
postLimit.append(" AND B.TORQUE$ROWNUM <= ")
.append(offset + limit);
}
}
else
{
postLimit.append(" B.TORQUE$ROWNUM <= ")
.append(limit);
}
query.setPreLimit(preLimit.toString());
query.setPostLimit(postLimit.toString());
query.setLimit(null);
// the query must not contain same column names or aliases.
// Find double column names and aliases and create unique aliases
// TODO: does not work for functions yet
UniqueList selectColumns = query.getSelectClause();
int replacementSuffix = 0;
Set columnNames = new HashSet();
// first pass: only remember aliased columns
// No replacements need to take place because double aliases
// are not allowed anyway
// So alias names will be retained
for (ListIterator columnIt = selectColumns.listIterator();
columnIt.hasNext();)
{
String selectColumn = (String) columnIt.next();
// check for sql function
if ((selectColumn.indexOf('(') != -1)
|| (selectColumn.indexOf(')') != -1))
{
// Sql function. Disregard.
continue;
}
// check if alias name exists
int spacePos = selectColumn.lastIndexOf(' ');
if (spacePos == -1)
{
// no alias, disregard for now
continue;
}
String aliasName = selectColumn.substring(spacePos + 1);
columnNames.add(aliasName);
}
// second pass. Regard ordinary columns only
for (ListIterator columnIt = selectColumns.listIterator();
columnIt.hasNext();)
{
String selectColumn = (String) columnIt.next();
// check for sql function
if ((selectColumn.indexOf('(') != -1)
|| (selectColumn.indexOf(')') != -1))
{
// Sql function. Disregard.
continue;
}
{
int spacePos = selectColumn.lastIndexOf(' ');
if (spacePos != -1)
{
// alias, already processed in first pass
continue;
}
}
// split into column name and tableName
String column;
{
int dotPos = selectColumn.lastIndexOf('.');
if (dotPos != -1)
{
column = selectColumn.substring(dotPos + 1);
}
else
{
column = selectColumn;
}
}
if (columnNames.contains(column))
{
// column needs to be aliased
// get replacement name
String aliasName;
do
{
aliasName = "a" + replacementSuffix;
++replacementSuffix;
}
while (columnNames.contains(aliasName));
selectColumn = selectColumn + " " + aliasName;
columnIt.set(selectColumn);
columnNames.add(aliasName);
}
else
{
columnNames.add(column);
}
}
}
/**
* This method is for the SqlExpression.quoteAndEscape rules. The rule is,
* any string in a SqlExpression with a BACKSLASH will either be changed to
* "\\" or left as "\". SapDB does not need the escape character.
*
* @return false.
*/
public boolean escapeText()
{
return false;
}
/**
* Whether an escape clause in like should be used.
* Example : select * from AUTHOR where AUTHOR.NAME like '\_%' ESCAPE '\';
*
* Oracle needs this, so this implementation always returns
* <code>true</code>.
*
* @return whether the escape clause should be appended or not.
*/
public boolean useEscapeClauseForLike()
{
return true;
}
}