如何在Entity Framework中获取SQL Server序列的下一个值？ [英] How to get next value of SQL Server sequence in Entity Framework?

问题描述

我想使用SQL Server sequence 对象在Entity Framework中显示数字序列，然后将其保存到数据库中。

I want to make use SQL Server sequence objects in Entity Framework to show number sequence before save it into database.

在当前的情况下，我在存储过程（先前的值存储在一个表中）中增加一个相关的事情，并将该值传递给C＃代码。

In current scenario I'm doing something related by increment by one in stored procedure (previous value stored in one table) and passing that value to C# code.

为了实现这一点，我需要一个表，但现在我想将其转换为序列对象（将给出有什么优势吗？）。

To achieve this I needed one table but now I want to convert it to a sequence object (will it give any advantage ?).

我知道如何在SQL Server中创建序列并获取下一个值。

I know how to create sequence and get next value in SQL Server.

但是我想知道如何在实体框架中获取SQL Server的序列对象的下一个值？

But I want to know how to get next value of sequence object of SQL Server in Entity Framework?

我无法在相关问题。

提前感谢

推荐答案

您可以创建一个简单的SQL Server中选择下列序列值的过程如下：

You can create a simple stored procedure in SQL Server that selects the next sequence value like this:

CREATE PROCEDURE dbo.GetNextSequenceValue 
AS 
BEGIN
    SELECT NEXT VALUE FOR dbo.TestSequence;
END

然后您可以将该存储过程导入到Entity Framework中的EDMX模型中，并调用该存储过程并获取序列值：

and then you can import that stored procedure into your EDMX model in Entity Framework, and call that stored procedure and fetch the sequence value like this:

// get your EF context
using (YourEfContext ctx = new YourEfContext())
{
    // call the stored procedure function import   
    var results = ctx.GetNextSequenceValue();

    // from the results, get the first/single value
    int? nextSequenceValue = results.Single();

    // display the value, or use it whichever way you need it
    Console.WriteLine("Next sequence value is: {0}", nextSequenceValue.Value);
}

更新：实际上，您可以跳过存储程序，并从您的EF上下文运行此原始SQL查询：

Update: actually, you can skip the stored procedure and just run this raw SQL query from your EF context:

public partial class YourEfContext : DbContext 
{
    .... (other EF stuff) ......

    // get your EF context
    public int GetNextSequenceValue()
    {
        var rawQuery = Database.SqlQuery<int>("SELECT NEXT VALUE FOR dbo.TestSequence;");
        var task = rawQuery.SingleAsync();
        int nextVal = task.Result;

        return nextVal;
    }
}

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