/* | |
* 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. | |
*/ | |
package org.apache.empire.db.oracle; | |
// Java | |
import java.util.Set; | |
import org.apache.empire.data.DataType; | |
import org.apache.empire.db.DBColumn; | |
import org.apache.empire.db.DBColumnExpr; | |
import org.apache.empire.db.DBDatabase; | |
import org.apache.empire.xml.XMLUtil; | |
import org.slf4j.Logger; | |
import org.slf4j.LoggerFactory; | |
import org.w3c.dom.Element; | |
/** | |
* implements a column expression for the Oracle rownum function | |
*/ | |
public class OracleRowNumExpr extends DBColumnExpr | |
{ | |
private final static long serialVersionUID = 1L; | |
private static final Logger log = LoggerFactory.getLogger(OracleRowNumExpr.class); | |
public final DBDatabase db; | |
/** | |
* Constructs a new OracleRowNumExpr object. | |
* | |
* @param db the database | |
*/ | |
public OracleRowNumExpr(DBDatabase db) | |
{ | |
this.db = db; | |
} | |
/** | |
* Returns the current DBDatabase object. | |
* @return the current DBDatabase object | |
*/ | |
@Override | |
public DBDatabase getDatabase() | |
{ | |
return db; | |
} | |
/** | |
* Returns the data type of the DBColumnExpr object. | |
* | |
* @return the data type | |
*/ | |
@Override | |
public DataType getDataType() | |
{ | |
return DataType.INTEGER; | |
} | |
/** | |
* Returns the column name. | |
* | |
* @return the column name | |
*/ | |
@Override | |
public String getName() | |
{ | |
return "rownum"; | |
} | |
/** this helper function calls the DBColumnExpr.addXML(Element, long) method */ | |
@Override | |
public Element addXml(Element parent, long flags) | |
{ | |
Element elem = XMLUtil.addElement(parent, "column"); | |
elem.setAttribute("name", getName()); | |
elem.setAttribute("function", "rownum"); | |
return elem; | |
} | |
/** | |
* Returns null. | |
* | |
* @return null | |
*/ | |
@Override | |
public DBColumn getUpdateColumn() | |
{ | |
return null; | |
} | |
/** | |
* Always returns false | |
* @return false | |
*/ | |
@Override | |
public boolean isAggregate() | |
{ | |
return false; | |
} | |
/** | |
* Creates the SQL-Command. | |
* | |
* @param buf the SQL-Command | |
* @param context the current SQL-Command context | |
*/ | |
@Override | |
public void addSQL(StringBuilder buf, long context) | |
{ | |
if (!(db.getDriver() instanceof DBDatabaseDriverOracle)) | |
{ | |
log.warn("Oracle RowNumExpression can be used with Oracle databases only!"); | |
} | |
buf.append("rownum"); | |
} | |
/** | |
* @see org.apache.empire.db.DBExpr#addReferencedColumns(Set) | |
*/ | |
@Override | |
public void addReferencedColumns(Set<DBColumn> list) | |
{ // nothing to do! | |
return; | |
} | |
/** | |
* @see java.lang.Object#equals(Object) | |
*/ | |
@Override | |
public boolean equals(Object other) | |
{ | |
return (other instanceof OracleRowNumExpr); | |
} | |
} |