CountStatement.cs :  » Persistence-Frameworks » Persist.NET » Persist » Statements » C# / CSharp Open Source

// Persist library : Persistence layer
// Copyright (C) 2003 Vincent Daron
// 
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
// 
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
// 
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

using System;
using System.Collections;

using Persist.Sql;
using Persist.Maps;
using Persist.Criteria;

namespace Persist.Statements{
   /// <summary>
   /// This Statement is used to create Query based on SELECT COUNT(*) ...
   /// </summary>
   public class CountStatement : PersistentStatement
   {
      private bool                 isDistinct = false;
      private CriteriaConditionSet havingCondition = null;

//      /// <summary>
//      /// Create a CountCriteria
//      /// </summary>
//      /// <param name="classMap">the associated classMap</param>
//      internal CountStatement(ClassMap classMap):base(classMap)
//      {
//         havingCondition = base.GetNewConditionSet();
//      }

      /// <summary>
      /// Create a Criteria from Type
      /// </summary>
      /// <param name="criteriaType">the Type used in this Criteria</param>
      public CountStatement(Type criteriaType):base(criteriaType)
      {
         havingCondition = base.GetNewConditionSet();
      }

      /// <summary>
      /// Returns CriteriaConditionSet for the HAVING part of this criteria.
      /// </summary>
      public CriteriaConditionSet HavingCondition
      {
         get
         {
            return havingCondition;
         }
      }

      /// <summary>
      /// Specified if the query must used the Distrinct SQL Keyword
      /// </summary>
      public bool Distinct
      {
         get{return isDistinct;}
         set{isDistinct = true;}
      }

      /// <summary>
      /// Returns sql statement for this criteria.
      /// </summary>
      /// <param name="parameters">Query Parameters</param>
      /// <returns>SqlStatement</returns>
      internal SqlStatement GetSqlStatement(ICollection parameters)
      {
         SqlStatement statement = null;

         statement = base.ClassMap.GetSelectCountSql(isDistinct);

         // Add 'FROM' clause to the select statement
         statement.AddSqlClause(" " + base.ClassMap.RelationalDatabase.ClauseStringFrom + " ");

         bool first = true;
         foreach(TableMap tableMap in base.Tables)
         {
            statement.AddSqlClause((!first ? ", " : "") + tableMap.Name);
            first = false;
         }

         // Fill statement with WHERE condition
         base.FillStatementWithWhere(statement, parameters);

         // Fill statement with HAVING condition
         if(havingCondition != null &&  havingCondition.Count > 0)
         {
            statement.AddSqlClause(" " + base.ClassMap.RelationalDatabase.ClauseStringHaving + " ");
            havingCondition.FillSqlStatement(statement, parameters);
         }

         return statement;
      }

      /// <summary>
      /// Execute the Query
      /// </summary>
      /// <param name="parameters">Query Parameter Values</param>
      /// <returns>the number of records</returns>
      public int Perform(ICollection parameters)
      {
         return Persist.PersistenceManagerFactory.Instance.ProcessStatementNonQuery(this, parameters);
      }
   }
}