一个自定义的C#数据库操作基础类 SqlHelper的代码

下面代码段是关于一个自定义的C#数据库操作基础类 SqlHelper的代码。
{
public class SQLHelper
{
private string strConn = null;
private SqlConnection Conn = null;
private SqlCommand Cmd = null;
private SqlDataReader Sqlsdr = null;
public SQLHelper()
{
strConn = ConfigurationManager.ConnectionStrings["strConn"].ConnectionString;
Conn = new SqlConnection(strConn);
}

private SqlConnection GetConn()
{
if (Conn.State == ConnectionState.Closed)
{
Conn.Open();
}
return Conn;
}


public int ExecuteNonQuery(string CmdText, CommandType CmdType)
{
int res;
try
{
Cmd = new SqlCommand(CmdText, GetConn());
Cmd.CommandType = CmdType;
res = Cmd.ExecuteNonQuery();

}
catch (Exception ex)
{

throw ex;
}
finally
{
if (Conn.State == ConnectionState.Open)
{
Conn.Close();
}
}
return res;
}

public int ExecuteNonQuery(string CmdText, SqlParameter[] Parameters, CommandType CmdType)
{
int res;
try
{
Cmd.Parameters.AddRange(Parameters);
Cmd = new SqlCommand(CmdText, GetConn());
Cmd.CommandType = CmdType;
res = Cmd.ExecuteNonQuery();
}
catch (Exception ex)
{

throw ex;
}
finally
{
if (Conn.State == ConnectionState.Open)
{
Conn.Close();
}
}
return res;
}


public DataTable ExecuteQuery(string CmdText, CommandType CmdType)
{
DataTable dt = new DataTable();

using (Sqlsdr = Cmd.ExecuteReader(CommandBehavior.CloseConnection))
{
Cmd = new SqlCommand(CmdText, GetConn());
Cmd.CommandType = CmdType;
dt.Load(Sqlsdr);
}
return dt;
}

public DataTable ExecuteQuery(string CmdText, SqlParameter[] Parameters, CommandType CmdType)
{
DataTable dt = new DataTable();

using (Sqlsdr = Cmd.ExecuteReader(CommandBehavior.CloseConnection))
{
Cmd = new SqlCommand(CmdText, GetConn());
Cmd.CommandType = CmdType;
Cmd.Parameters.AddRange(Parameters);
dt.Load(Sqlsdr);
}
return dt;
}
}
}