/// <summary>
/// 根据当前的表达式，获取Command
/// </summary>
private DbCommand CreateCurrentCommand()
{
var traslater = new ExpressionTranslater(this.DbProvider, this.Expression);
traslater.Translate();
var command = DbProvider.CreateCommand(traslater.CommandText, traslater.Params.ToArray());
return(command);
}
