package org.apache.ojb.broker.accesslayer.sql;
/* Copyright 2004-2005 The Apache Software Foundation
*
* Licensed 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 org.apache.ojb.broker.OJBRuntimeException;
import org.apache.ojb.broker.metadata.ClassDescriptor;
import org.apache.ojb.broker.metadata.FieldDescriptor;
import org.apache.ojb.broker.util.logging.Logger;
/**
* Generate a select to check existence of an object.
* Something like "SELECT id_1 FROM myTable where id_1 = 123 and id_2 = 'kjngzt'".
*
* @author <a href="mailto:arminw@apache.org">Armin Waibel</a>
* @version $Id: SqlExistStatement.java,v 1.4.2.2 2005/12/21 22:23:44 tomdz Exp $
*/
public class SqlExistStatement extends SqlPkStatement
{
private static final String SELECT = "SELECT ";
private static final String FROM = " FROM ";
private String sql;
public SqlExistStatement(ClassDescriptor aCld, Logger aLogger)
{
super(aCld, aLogger);
}
/** Return SELECT clause for object existence call */
public String getStatement()
{
if(sql == null)
{
StringBuffer stmt = new StringBuffer(128);
ClassDescriptor cld = getClassDescriptor();
FieldDescriptor[] fieldDescriptors = cld.getPkFields();
if(fieldDescriptors == null || fieldDescriptors.length == 0)
{
throw new OJBRuntimeException("No PK fields defined in metadata for " + cld.getClassNameOfObject());
}
FieldDescriptor field = fieldDescriptors[0];
stmt.append(SELECT);
stmt.append(field.getColumnName());
stmt.append(FROM);
stmt.append(cld.getFullTableName());
appendWhereClause(cld, false, stmt);
sql = stmt.toString();
}
return sql;
}
}