对方法重载感到困惑

Question

我正在使用.NET 4.0与ASP.NET 4.0和C#(那将是C#4.0？).

我想在我的SQL Server数据库中插入一些数据,我有一个这样的方法来处理这个:

public int InsertTrade(
    string symbol,
    string tradeSetupId,
    int tradeTypeId,
    decimal lotsPerUnit,
    string chartTimeFrame,
    int tradeGrade,
    int executionGrade,
    int MFEPips,
    int MAEPips,
    decimal pctAccountRisked
    )
{
    SqlCommand cmd = new SqlCommand("usp_InsertTrade");
    cmd.Parameters.AddWithValue("@symbol", symbol);
    cmd.Parameters.AddWithValue("@pctAccountRisked", pctAccountRisked);
    cmd.Parameters.AddWithValue("@tradeSetupId", tradeSetupId);
    cmd.Parameters.AddWithValue("@lotsPerUnit", lotsPerUnit);
    cmd.Parameters.AddWithValue("@tfCode", chartTimeFrame);
    cmd.Parameters.AddWithValue("@MAEPips", MAEPips);
    cmd.Parameters.AddWithValue("@MFEPips", MFEPips);
    cmd.Parameters.AddWithValue("@tradeGrade", tradeGrade);
    cmd.Parameters.AddWithValue("@executionGrade", executionGrade);
    return (InsertData(cmd, "trade"));
}

有几个非必填字段:tradeGrade,executionGrade,MFEPips,MAEPips.usp_InsertTrade存储过程将这些可选参数公开为NULLable.在C#中编写代码的最佳方法是什么？我正在学习编程,所以如果能提供最佳实践指导,那就太棒了.

以下是usp_InsertTrade的存储过程参数:

CREATE procedure [dbo].[usp_InsertTrade]
@symbol char(6),
@tradeSetupId varchar(10),
@tradeTypeId int,
@lotsPerUnit decimal(18,1),
@chartTimeFrame varchar(5),
@tradeGrade smallint = NULL,
@executionGrade smallint = NULL,
@MFEPips int = NULL,
@MAEPips int = NULL,
@pctAccountRisked decimal(3,2)
AS

非常感谢.

UPDATE

我已经改变了我的功能,以便可选参数位于底部.像这样:

public int InsertTrade(
    string symbol,
    string tradeSetupId,
    int tradeTypeId,
    decimal lotsPerUnit,
    string chartTimeFrame,
    decimal pctAccountRisked,
    int? tradeGrade,
    int? executionGrade,
    int? MFEPips,
    int? MAEPips
    )
{
    SqlCommand cmd = new SqlCommand("usp_InsertTrade");
    // required parameters
    cmd.Parameters.AddWithValue("@symbol", symbol);
    cmd.Parameters.AddWithValue("@tradeSetupId", tradeSetupId);
    cmd.Parameters.AddWithValue("@tradeTypeId", tradeTypeId);
    cmd.Parameters.AddWithValue("@lotsPerUnit", lotsPerUnit);
    cmd.Parameters.AddWithValue("@tfCode", chartTimeFrame);
    cmd.Parameters.AddWithValue("@pctAccountRisked", pctAccountRisked);

    // optional parameters
    if (MAEPips.HasValue)
        cmd.Parameters.AddWithValue("@MAEPips", MAEPips);
    if (MFEPips.HasValue)
        cmd.Parameters.AddWithValue("@MFEPips", MFEPips);
    if (tradeGrade.HasValue)
        cmd.Parameters.AddWithValue("@tradeGrade", tradeGrade);
    if (executionGrade.HasValue)
        cmd.Parameters.AddWithValue("@executionGrade", executionGrade);
    return (InsertData(cmd, "trade"));
}

当我使用此代码调用该函数时:

DBUtil DB = new DBUtil();
int tradeId = DB.InsertTrade (
    ddlSymbols.SelectedValue,
    ddlTradeSetups.SelectedValue, 
    ddlTradeTypes.SelectedValue, 
    decimal.Parse(txtLotsPerUnit.Text),
    ddlTimeFrames.Text,
    decimal.Parse(txtAcctRisk.Text));

我收到此错误:

No overload for method 'InsertTrade' takes 6 arguments

Answer 1

使用C#4.0,您可以将可选参数与可空类型结合使用:

public int InsertTrade(
    string symbol,
    string tradeSetupId,
    int tradeTypeId,
    decimal lotsPerUnit,
    string chartTimeFrame,
    decimal pctAccountRisked,
    int? tradeGrade = null,
    int? executionGrade = null,
    int? MFEPips = null,
    int? MAEPips = null
    )
{
    SqlCommand cmd = new SqlCommand("usp_InsertTrade");
    cmd.Parameters.AddWithValue("@symbol", symbol);
    cmd.Parameters.AddWithValue("@pctAccountRisked", pctAccountRisked);
    cmd.Parameters.AddWithValue("@tradeSetupId", tradeSetupId);
    cmd.Parameters.AddWithValue("@lotsPerUnit", lotsPerUnit);
    cmd.Parameters.AddWithValue("@tfCode", chartTimeFrame);
    if(MAEPips.HasValue)
        cmd.Parameters.AddWithValue("@MAEPips", MAEPips);
    if(MFEPips.HasValue)
        cmd.Parameters.AddWithValue("@MFEPips", MFEPips);
    if(tradeGrade.HasValue)
        cmd.Parameters.AddWithValue("@tradeGrade", tradeGrade);
    if(executionGrade.HasValue)
        cmd.Parameters.AddWithValue("@executionGrade", executionGrade);
    return (InsertData(cmd, "trade"));
}

有了这么多参数,您可能需要考虑引入参数对象重构 - 它将使您的代码在将来更容易阅读和修改.