我应该使用 C# 中的哪种数据类型将数据输入到 T-SQL 中的十进制列中？

Question

我很难弄清楚我将在 C# 中使用哪种数据类型将数据输入到我的数据库中包含小数 (5,2) 的表中。当我尝试使用 C# 十进制数据类型时，它说将数字转换为十进制时出错。当我尝试字符串时，它说它无法将 nvarchar 转换为十进制。当我尝试浮动时......同样的事情发生了，除了借口是“真正的”数据类型。 double 也失败了。

我有一个存储过程，可以将数据输入到我的表中，但是在我运行存储过程中的数据类型并将其转换为实际的十进制之前，有没有其他方法可以转换 ac# 数据类型以适应我的小数（5,2）字段？

private void btnAddClientComputer_Click(object sender, EventArgs e)
{
    SQLCommands comm = new SQLCommands();
    try
    {
        comm.AddClientComputer(int.Parse(cbCustomerID.Text), cbAction.Text, decimal.Parse(tbCost.Text));
    }
    catch (FormatException)
    {
        MessageBox.Show("The cost you have entered is invalid. Please ensure the cost is above 0, and is an actual number", "Invalid Input at Cost", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
    }
}

...

public void AddClientComputer(int CustomerID, string Action, decimal Cost)
{
    try
    {
        comm = new SqlCommand("UspAddClientComputer", conn); // Stored Procedure - see sql file
        comm.Parameters.AddWithValue("@CustomerID", CustomerID);
        comm.Parameters.AddWithValue("@Action", Action);
        comm.Parameters.AddWithValue("@Cost", Cost);
        comm.CommandType = CommandType.StoredProcedure;
        comm.ExecuteNonQuery();
    }
    catch (Exception ex)
    {
        System.Windows.Forms.MessageBox.Show(ex.Message, "Error", System.Windows.Forms.MessageBoxButtons.OK, System.Windows.Forms.MessageBoxIcon.Error);
    }
}

...

CREATE TABLE ClientComputers
            (ClientComputerID int Identity(1,1) primary key clustered
            ,CustomerID int
            ,Action varchar(7) check (Action = 'Upgrade' OR Action = 'Store')
            ,Cost decimal(5,2) check (Cost > 0)
            ,Constraint FKCustomerComputer FOREIGN KEY (CustomerID) REFERENCES Customers(CustomerID));
Go

...

CREATE PROCEDURE uspAddClientComputer @CustomerID int, @Action varchar(7), @Cost decimal(5,2)
AS
BEGIN TRY
    BEGIN TRANSACTION TrnAddClientComputer;
     INSERT INTO [TCTdb].[dbo].[ClientComputers]
           ([CustomerID]
           ,[Action]
           ,[Cost])
     VALUES
           (@CustomerID
           ,@Action
           ,@Cost)
    COMMIT TRANSACTION TrnAddClientComputer;
END TRY
BEGIN CATCH
    ROLLBACK TRANSACTION TrnAddClientComputer;

    DECLARE @ErrorMessage NVARCHAR(4000);
    DECLARE @ErrorSeverity INT;
    DECLARE @ErrorState INT;

    SELECT 
        @ErrorMessage = ERROR_MESSAGE(),
        @ErrorSeverity = ERROR_SEVERITY(),
        @ErrorState = ERROR_STATE();

    RAISERROR (@ErrorMessage,
               @ErrorSeverity,
               @ErrorState
               );
END CATCH
GO

Answer 1

在这种情况下，我找到了解决问题的方法，感谢 sll 引起了我的注意。以下代码对我有用。

private void btnAddClientComputer_Click(object sender, EventArgs e)
{
    SQLCommands comm = new SQLCommands();
    double trycost;
    if (double.TryParse(tbCost.Text,out trycost))
    {
        comm.AddClientComputer(int.Parse(cbCustomerID.Text), cbAction.Text, trycost);
    }
    else
    {
        MessageBox.Show("The cost you have entered is invalid. Please ensure the cost is above 0, and is an actual number", "Invalid Input at Cost", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
    }
}

...

public void AddClientComputer(int CustomerID, string Action, double Cost)
    {
        try
        {
            comm = new SqlCommand("UspAddClientComputer", conn); // Stored Procedure - see sql file
            comm.Parameters.AddWithValue("@CustomerID", CustomerID);
            comm.Parameters.AddWithValue("@Action", Action);
            comm.Parameters.Add(new SqlParameter("@Cost",Cost));
            comm.CommandType = CommandType.StoredProcedure;
            comm.ExecuteNonQuery();
        }
        catch (Exception ex)
        {
            System.Windows.Forms.MessageBox.Show(ex.Message, "Error", System.Windows.Forms.MessageBoxButtons.OK, System.Windows.Forms.MessageBoxIcon.Error);
        }
    }

..这里是解决方案部分。我用 smallmoney 替换了 Decimal(5,2)。

CREATE TABLE ClientComputers
            (ClientComputerID int Identity(1,1) primary key clustered
            ,CustomerID int
            ,Action varchar(7) check (Action = 'Upgrade' OR Action = 'Store')
            ,Cost smallmoney check (Cost > 0)
            ,Constraint FKCustomerComputer FOREIGN KEY (CustomerID) REFERENCES Customers(CustomerID));
Go

---------STORED PROCEDURES
--ADD CLIENT COMPUTER
CREATE PROCEDURE uspAddClientComputer @CustomerID int, @Action varchar(7), @Cost smallmoney
AS
BEGIN TRY
    BEGIN TRANSACTION TrnAddClientComputer;
     INSERT INTO [TCTdb].[dbo].[ClientComputers]
           ([CustomerID]
           ,[Action]
           ,[Cost])
     VALUES
           (@CustomerID
           ,@Action
           ,@Cost)
    COMMIT TRANSACTION TrnAddClientComputer;
END TRY
BEGIN CATCH
    ROLLBACK TRANSACTION TrnAddClientComputer;

    DECLARE @ErrorMessage NVARCHAR(4000);
    DECLARE @ErrorSeverity INT;
    DECLARE @ErrorState INT;

    SELECT 
        @ErrorMessage = ERROR_MESSAGE(),
        @ErrorSeverity = ERROR_SEVERITY(),
        @ErrorState = ERROR_STATE();

    RAISERROR (@ErrorMessage,
               @ErrorSeverity,
               @ErrorState
               );
END CATCH
GO

感谢所有尝试过的人。这回答了我的问题。正确的想法，错误数据类型。

Answer 2

我建议您添加指定类型的小数参数。这意味着不仅要使用 AddWithValue，还要创建一个 Parameter 对象。

我怀疑问题是由于代码无法干净地转换而引起的。

预计到达时间：

你的代码是

comm.Parameters.Add("@Cost",SqlDbType.Decimal);
comm.Parameters["@Cost"].Value = Cost;

你需要做一些类似的事情（正如我所说，我没有容易获得的语法检查）

SqlParameter param= new SqlParameter("@Cost", SqlDbType.Decimal, Cost);//there are more parameters which I cannot remember
comm.Parameters.Add(param);

重要的是创建一个可以传入所有参数的对象，这些参数可以清楚地定义为 SQL 小数。

Answer 3

试试

 comm.Parameters.Add(new SqlParameter("@Cost", Cost));

顺便说一句，

你可以重构下面的块

 try
    {
        comm.AddClientComputer(int.Parse(cbCustomerID.Text), cbAction.Text, decimal.Parse(tbCost.Text));
    }
    catch (FormatException)
    {
        MessageBox.Show("The cost you have entered is invalid. Please ensure the cost is above 0, and is an actual number", "Invalid Input at Cost", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
    }

到

// TODO: do the same for int.Parse as well
decimal userDefinedCost;
if (decimal.TryParse(tbCost.Text, out userDefinedCost))
{
     comm.AddClientComputer(int.Parse(cbCustomerID.Text), cbAction.Text, userDefinedCOst);
}
else
{
     MessageBox.Show("The cost you have entered is invalid. Please ensure the cost is above 0, and is an actual number", "Invalid Input at Cost", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
}