npgsqlfactory.cs

抽象工厂的典型实现

using System;
using System.Data;
using System.Data.Common;
using System.Collections;

#region 版权声明
///
/// 版权所有(C)2005,2006  作者：漆巧林。保留所有权利, [e-mail], [e-mail]
/// 
/// 作者不对本代码提供任何保证，因此，对于使用该代码带来的损害或者潜在的损害，作者不承担责任。
/// 在满足如下的条件下，你可以自由使用该代码：
/// 1. 非商业应用
/// 2. 保留本版权声明
/// 要进行商业应用，必须得到作者的书面许可。
/// 你可以修改和自由发布本代码，条件是保留前述的版权声明。
/// 
#endregion

namespace DataAccess
{
	/// <summary>
	/// NpgsqlFactory :Postgres数据库访问具体工厂。
	/// </summary>
	public class NpgsqlFactory : DbFactory
	{
		public override IDbConnection CreateConnection()
		{
			return new Npgsql.NpgsqlConnection();
		}

		public override IDbConnection CreateConnection(string connectionString)
		{
			return new Npgsql.NpgsqlConnection(connectionString);
		}

		public override IDbDataAdapter CreateAdapter()
		{
			return new Npgsql.NpgsqlDataAdapter();
		}
		public override IDbDataAdapter CreateAdapter(IDbCommand selectCommand)
		{
			return new Npgsql.NpgsqlDataAdapter((Npgsql.NpgsqlCommand)selectCommand);
		}
		public override IDbDataAdapter CreateAdapter(string selectCommandText, IDbConnection selectConnection)
		{
			return new Npgsql.NpgsqlDataAdapter(selectCommandText, (Npgsql.NpgsqlConnection)selectConnection);
		}
		public override IDbDataAdapter CreateAdapter(string selectCommandText, string selectConnectionString)
		{
			return new Npgsql.NpgsqlDataAdapter(selectCommandText, selectConnectionString);
		}

		public override IDbCommand CreateCommand()
		{
			return new Npgsql.NpgsqlCommand();
		}
		public override IDbCommand CreateCommand(string cmdText)
		{
			return new Npgsql.NpgsqlCommand(cmdText);
		}
		public override IDbCommand CreateCommand(string cmdText, IDbConnection connection)
		{
			return new Npgsql.NpgsqlCommand(cmdText, (Npgsql.NpgsqlConnection)connection);
		}
		public override IDbCommand CreateCommand(string cmdText, IDbConnection connection, IDbTransaction transaction)
		{
			return new Npgsql.NpgsqlCommand(cmdText, (Npgsql.NpgsqlConnection)connection, (Npgsql.NpgsqlTransaction)transaction);
		}

		public override DbCommandBuilder CreateCommandBuilder()
		{
			return new DataAccess.NpgsqlCommandBuilder();
		}
		public override DbCommandBuilder CreateCommandBuilder(IDbDataAdapter adapter)
		{
			return new DataAccess.NpgsqlCommandBuilder(adapter);
		}

		protected override void AppendItem(IDbCommand cmd, ConditionList.ConditionItem item, bool bFirst)
		{
			if(bFirst)
				cmd.CommandText += " WHERE";
			else
				cmd.CommandText += " AND";
			if(item.FieldValue is DBNull)
				cmd.CommandText += String.Format(" {0} IS NULL", item.FieldName);
			else if(item.Relation == '%')
				cmd.CommandText += String.Format(" {0} LIKE '%{1}%'", item.FieldName, item.FieldValue);
			else
			{
				IDbDataParameter param = cmd.CreateParameter();
				param.SourceColumn = item.FieldName;
				param.ParameterName = "p"+ this.nParam++;
				param.Value = item.FieldValue;

				cmd.CommandText += String.Format(" {0} {1} {2}", item.FieldName, item.Relation, param.ParameterName);
				cmd.Parameters.Add(param);
			}
		}

		public override void AppendCommandCondition(IDbCommand cmd, string clause, string fieldName, String relation, object fieldValue)
		{
			IDbDataParameter param = cmd.CreateParameter();
			param.SourceColumn = fieldName;
			param.ParameterName = fieldName;
			param.Value = fieldValue;
			if(fieldValue is DBNull)
			{
				cmd.CommandText += String.Format(" {0} {1} IS NULL", clause, fieldName);
			}
			else
			{
				cmd.CommandText += string.Format(" {0} {1} {2} {3}", clause, fieldName, relation, param.ParameterName);
			}
			cmd.Parameters.Add(param);
		}

		public override IDbCommand CreateIdentityGetter(string tableName)
		{
			throw new ApplicationException("Function Not Implemented");
		}

		public override IDbInitiationHelper CreateInitiationHelper( IDbConnection connection )
		{
			return new NpgsqlInitiationHelper(connection);
		}

		public override IDbInitiationHelper CreateInitiationHelper( string connectionString )
		{
			return new NpgsqlInitiationHelper(connectionString);
		}
	}
}