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 1.1 2007-08-24 22:17:39 ewestfal 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;

     }

 }