尽管已设置精度，但MSSQL表中的十进制数会四舍五入 [英] Decimal number in MSSQL table gets rounded although precision is set

问题描述

我的c#对象具有十进制属性:

My c# object has a decimal property:

public decimal LastPrice { get; set; }

在处理对象时，将设置十进制值.例如:

While processing my object, the decimal value gets set. For example:

LastPrice = 0.091354;

我修改了DbContext来提高十进制精度，如另一篇stackoverflow文章所述:

I modified my DbContext to increase the decimal precision as explained in another stackoverflow post:

protected override void OnModelCreating(ModelBuilder modelBuilder)
{       
        foreach (var property in modelBuilder.Model.GetEntityTypes()
            .SelectMany(t => t.GetProperties())
            .Where(p => p.ClrType == typeof(decimal) || p.ClrType == typeof(decimal?)))
        {
            property.SetColumnType("decimal(38, 10)");
        }        
}

Microsoft Sql Server Management Studio中的表设计视图反映了此配置.这是从SSMS编写的脚本表:

The tables design view in Microsoft Sql Server Management Studio reflects this configuration. Here is the table scripted from SSMS:

CREATE TABLE [dbo].[TradedCurrencyPairs](
    [Id] [int] IDENTITY(1,1) NOT NULL,
    [LastPrice] [decimal](38, 10) NOT NULL,
...

当我在调试过程中检查对象(将其添加到我的DbContext中)时，它看起来不错:

When I check the object during debugging as it gets added to my DbContext, it looks good:

但是在数据库中，最终结果为0.0000000000.

But in the database it ends up as being 0.0000000000.

据我所知，该值仍在四舍五入，就好像它的精度为2一样.应该为0.09232的值将变为0.0900000000.因此，所有小数点仍然会减少.

As far as I can tell, the value is still being rounded as if it would have a precision of 2. A value that should be 0.09232 becomes 0.0900000000. So all decimals still get cut.

我尝试了几种不同的数据注释:

I have tried several different Data Annotations:

// [PrecisionAndScale(20, 10)]
//[RegularExpression(@"^\d+\.\d{20,10}$")]
//[Range(0, 99999999999999999999.9999999999)]
[Range(typeof(decimal), "20", "10")]

但是他们没有帮助.从SSMS插入数据可以正常工作:插入交易货币对值('tzt'，'ttt'，'rrrr'，'20120618 10:34:09 AM'，'hgghghg'，0.123456、1、0.123456789、0.123456、0.123456)；去

but they didn't help. Inserting data from SSMS works fine: INSERT INTO TradedCurrencyPairs VALUES ('tzt', 'ttt', 'rrrr', '20120618 10:34:09 AM' , 'hgghghg', 0.123456, 1, 0.123456789, 0.123456, 0.123456); go

我的DbModelSnapshot列如下所示:

My DbModelSnapshot for the column looks like this:

            b.Property<decimal>("LastPrice")
                .HasPrecision(10)
                .HasColumnType("decimal(20, 10)");

我也尝试过:

TradedCurrencyPair TestPair = new TradedCurrencyPair("one", "two", "Bibox", DateTime.Now, "unknown", 0.1234567890M, 1, 0.1234567890M, 0.1234567890M, 0.1234567890M);
                context.TradedCurrencyPairs.Add(TestPair);
                context.SaveChanges(); 

结果是一样的...

在设置该值与在数据库中结束之间的某个地方，它会被修改:/

Somewhere between setting the value and it ending up in the database, it gets modified :/

这是SQL表:

/****** Object:  Table [dbo].[TradedCurrencyPairs]    Script Date: 25/07/2020 09:32:32 ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

CREATE TABLE [dbo].[TradedCurrencyPairs](
    [Id] [int] IDENTITY(1,1) NOT NULL,
    [TradedCurrency] [nvarchar](max) NULL,
    [BaseCurrency] [nvarchar](max) NULL,
    [Exchange] [nvarchar](max) NULL,
    [DateTime] [datetime2](7) NOT NULL,
    [TransactionType] [nvarchar](max) NULL,
    [LastPrice] [decimal](20, 10) NOT NULL,
    [ExchangeInternalPairId] [int] NOT NULL,
    [High24h] [decimal](20, 10) NOT NULL,
    [Low24h] [decimal](20, 10) NOT NULL,
    [Volume24h] [decimal](20, 10) NOT NULL,
 CONSTRAINT [PK_TradedCurrencyPairs] PRIMARY KEY CLUSTERED 
(
    [Id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, OPTIMIZE_FOR_SEQUENTIAL_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
GO

不使用实体框架的工作方式:

SqlCommand command = new SqlCommand("insert into TradedCurrencyPairs values('one', 'two', 'Bibox', convert(datetime, '18-06-12 10:34:09 PM', 5), 'unknown', 0.1234567890, 1, 0.1234567890, 0.1234567890, 0.1234567890); ", cnn);
This way the decimals do not get modified. So EF causes the issue.

有人可以向我解释我做错了什么吗?

Could anybody please explain to me what I am doing wrong?

非常感谢！

推荐答案

当我从此处发布代码时:

When I posted the code from here:

实体框架核心-将小数精度和小数位数设置为所有小数属性

我仍然习惯使用EF Core 3，因此我启用了EF Core 3的代码.我不记得我使用Beta软件包并将它们更新为EF Core 5预览.

I was still used to using EF Core 3, so I enabled the code for EF Core 3. I didn't remember I use beta packages and had them updated to EF Core 5 preview.

所以使用这个:

    foreach (var property in modelBuilder.Model.GetEntityTypes()
        .SelectMany(t => t.GetProperties())
        .Where(p => p.ClrType == typeof(decimal) || p.ClrType == typeof(decimal?)))
    {
        
       // EF Core 3
       // property.SetColumnType("decimal(20, 10)");
       // property.SetPrecision(10);
        
        // EF Core 5
        property.SetPrecision(18);
        property.SetScale(6);
    }

代替此:

    foreach (var property in modelBuilder.Model.GetEntityTypes()
        .SelectMany(t => t.GetProperties())
        .Where(p => p.ClrType == typeof(decimal) || p.ClrType == typeof(decimal?)))
    {
        
        EF Core 3
        property.SetColumnType("decimal(20, 10)");
        property.SetPrecision(10);
        
        // EF Core 5
        // property.SetPrecision(18);
        // property.SetScale(6);
    }

工作完美.

对不起，由于我的愚蠢错误，我浪费了您的时间:/

I'm sorry that I have wasted your time because of my stupid mistake :/

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